Young Adult franchises have been all the rage in Hollywood over the last decade. Ever since the massive success of the original Twilight, studios have scrambled to continue catching lightning in a bottle. Some of the subsequent efforts have been similarly successful. Others have outright flopped, occasionally faltering after just one entry. Either way, the belief persists that YA franchises are a potential gold mine.

That may or may not be true. One thing that is definitely true, however, is that they are hotbeds for romance. In case after case, YA franchises have helped spawn love behind the scenes. Stars from some of your favorite series have dated, and in a couple of cases, even gotten married. Love affairs have occurred on movie sets since the dawn of cinema, but something about this type of film seems to inspire them to happen more often.

On the flip side, there have also been a number of notable cases where costars didn't date, but did form very meaningful friendships. These platonic relationships have played out in front of the media and adoring fans in the most charming of ways. Seeing the camaraderie between actors helps build an appreciation for the movies themselves, because you know the parties involved genuinely enjoyed working together.

What follows is a breakdown of some of the most notable romances between YA franchise stars and some of the most endearing friendships. We'll tell you which celebs fell for each other and which became lifelong pals.

Here are 10 YA Franchise Stars Who Dated In Real Life (And 6 Who Are Just Best Friends).

Dated: Logan Lerman and Alexandra Daddario (Percy Jackson)

Logan Lerman and Alexandra Daddario as Percy and Annabeth in Percy Jackson

The Percy Jackson franchise wasn't the biggest or most popular YA adaptation, but it did spawn two installments -- Percy Jackson & the Olympians: The Lightning Thief, and Percy Jackson: Sea of Monsters.

Nevertheless, two of the series' very likable stars became seriously involved with one another, reportedly almost making it to the altar. Logan Lerman, who plays the title character, dated Alexandra Daddario. She portrays a demigod named Annabeth. Even though the movies didn't get great reviews, the chemistry between them was noticeable onscreen.

The couple largely kept their relationship out of the spotlight, although it was serious enough that they reportedly got engaged in 2016. Within a year, it was off.

Daddario was later linked to her Baywatch co-star Zac Efron. Lerman, on the other hand, hasn't been publicly attached to anyone since their relationship ended.

Dated: Bonnie Wright and Jamie Campbell Bower (Harry Potter)

Bonnie Wright and Jamie Campbell Bower

She played Ginny Weasley, the sister of Harry Potter's best friend Ron. He played the young Gellert Grindelwald in Harry Potter and the Deathly Hallows – Part 1. We're talking, of course, about Bonnie Wright and Jamie Campbell Bower.

Wright and Bower first got together in 2009, although they didn't publicly acknowledge it until 2010, when they arrived at the BAFTA awards together.

After nearly two years of dating, the couple became engaged in April 2011. A

little over a year later, though, the engagement was off. They declined to provide specifics to the press – and therefore their fans – but it was rumored that they'd broken up several months before news of it went public. Their split was said to be amicable.

Friends: Shailene Woodley and Ansel Elgort (Divergent, The Fault in Our Stars)

Gus and Hazel The Fault in Our Stars Movie

Shailene Woodley and Ansel Elgort have appeared in not one, but two YA adaptations together: the Divergent saga and The Fault in Our Stars.

Particularly in that latter film, the actors really generate some magic. With so much palpable heat, they must have had something going on off-camera, right? Wrong -- at least according to Elgort, who insisted to Seventeen magazine that he and Woodley are just good pals and nothing else. "Me and Shailene have a really platonic relationship," he declared. "I’ve never once wanted her [physically], which is nice."

Their friendship continues to this day. In May of 2018, they had a reunion at the fancy Met Gala, even posing together for pictures.

Despite the absence of romantic interest, fans undoubtedly hope they'll ignite sparks again in a movie sometime in the future.

Dated: Sarah Hyland and Dominic Sherwood (Vampire Academy)

Sarah Hyland and Dominic Sherwood

In 2014, Modern Family star Sarah Hyland appeared in the movie version of Richelle Mead's novel Vampire Academy. Not much came of it; the film was a critical and commercial dud.

That said, she did get a boyfriend out of the gig, specifically fellow cast member Dominic Sherwood. Their relationship was pretty hot and heavy. The actress even posted an Instagram video of them making out in an elevator.

The romance lasted for two whole years, which is fairly long for Hollywood hook-ups.

During the summer of 2017, though, People magazine broke the scoop that Hyland and Sherwood had split up. As is often the case in these matters, there was a statement that they would "remain friends."

Hyland went on to date Wells Adams, a veteran of The Bachelorette, while Sherwood started seeing model Niamh Adkins.

Friends: Dylan O'Brien and Kaya Scodelario (The Maze Runner)

Kaya Scodelario and Dylan O'Brien in The Maze Runner

Dylan O'Brien and Kaya Scodelario both saw their stock rise considerably with the release of the Maze Runner movies. He plays Thomas, a teenage boy who has to navigate a booby trap-filled maze in order to survive. She is Teresa, the first-ever girl to arrive in the “Glade” – the walled-in area where Thomas and a group of other boys have formed their own society.

Maybe because so many YA franchise stars have dated, fans and the media were quick to want to make the two actors an item. The truth is that they're just really good friends. Scodelario told Collider, that her co-star is “like my little brother. He’s very cool. It’s great working with him. He’s got so much energy. He’s so much fun. I really love him. He’s a dude.”

Dated: Kristen Stewart and Robert Pattinson (Twilight)

Robert Pattinson as Edward and Kristen Stewart as Bella Twilight.jpg

Of all the YA adaptation stars who dated, there is no more famous example than Twilight's Kristen Stewart and Robert Pattinson. The duo met on the set of the 2008 original and immediately became an item. It was almost too perfect. Given the fans' passionate devotion to the love story between Edward and Bella, the idea that the actors portraying them were also in love induced some hardcore swooning.

Stewart and Pattinson dated for four years, broke up in 2012, then briefly reconciled before splitting for good in 2013. Or did they?

As recently as June of this year, rumors started swirling that they were back together after The Daily Mail snapped pictures of them at L.A.'s Chateau Marmont. Regardless of what happens, the relationship between the Twilight stars helped fuel the popularity of the films they made together.

Dated: Zac Efron and Vanessa Hudgens (High School Musical)

Troy and Gabriella dance on the roof in High School Musical 3

Zac Efron and Vanessa Hudgens became young Hollywood royalty when they starred in the Disney Channel's pop culture phenomenon High School Musical and its two sequels.

After meeting on the set, they started dating, spending a total of five years together.

What went wrong? Hudgens has said that Efron's rising popularity was a major factor. A lot of girls were after him, which made being his companion difficult. "I went through a phase when I was really mean because I was so fed up. Girls were running after him, and I was giving them death stares," the actress told the New York Times.

Some fans have held out hope that they would someday reunite. That seems like a complete no-go. Hudgens told Us Weekly that she has "completely lost touch" with her ex.

Friends: Jennifer Lawrence and Josh Hutcherson (The Hunger Games)

Josh Hutcherson and Jennifer Lawrence

The Hunger Games stars Jennifer Lawrence and Josh Hutcherson don't love each other in a romantic sense, but it's crystal clear that they love each other in a brother-and-sister kind of way.

The two have repeatedly goofed around with -- and occasionally busted on -- one another in interviews. They play-argue for reporters one minute, then turn around and get all touchy-feely. When the Hunger Games series was finished, Teen Vogue asked them if they ever got on each other's nerves. She joked that she wouldn't miss him "spitting spit bubbles," while he cracked that he wouldn't miss her "making us late to things."

Their playful friendship is adorable. Hutcherson once told British GQ, "If Jennifer and I were at all attracted to each other, it would be the most intense relationship in the world."

Dated: Ian Somerhalder (The Vampire Diaries) and Nikki Reed (Twilight)

Ian Somerhalder and Nikki Reed

Most of the romances on this list are between actors who appeared in the same franchise. This one is a little different, although it has vampires in common. Ian Somerhalder of The Vampire Diaries is married to Nikki Reed from Twilight.

Both were in high-profile relationships before getting together. He previously dated co-star Nina Dobrev, while she was married to former American Idol contestant Paul McDonald. When they met each other, after both becoming single, the attraction was instant, leading to a steady relationship and eventually a marriage.

The couple has not been without controversy.

During an appearance on a podcast, Somerhalder revealed that he threw away his wife's birth control pills. Some listeners took that as him making the decision to have children for both of them. Reed cleared it up, stating that it was a mutual decision.

Friends: Emma Watson and Daniel Radcliffe (Harry Potter)

Daniel Radcliffe and Emma Watson

Harry Potter fans would probably have liked nothing better than to see stars Daniel Radcliffe and Emma Watson become an item. It was not to be, though. They just have a strong friendship, formed over the course of eight movies together.

Radcliffe told The Guardian, "There was never anybody I fancied that much in the cast, though the conspiracy theorists always like to say that me and Emma are dating. We know it'd be everything the fans ever wanted. I'm sorry guys, it's not happening. It's just not. There's something really incestuous about the idea of it."

The actor also told the Sunday Mirror that, while he has no contact with fellow Potter star Rupert Grint, he and Watson are in constant communication. "Emma and I text all the time," he said.

Dated: Dianna Agron and Alex Pettyfer (I Am Number Four)

Alex Pettyfer and Dianna Agron in I Am Number Four

I Am Number Four stars Alex Pettyfer and Dianna Agron had kind of a crazy thing going on. They started dating while the movie was being filmed, only to break up the day after it was released, despite rumors that they were engaged.

E! Online suggested that the relationship wasn't healthy, due to Pettyfer's behavior. A source told them that the actor was "a little controlling," and that he obsessively insisted on reading her text messages because he was worried that she would cheat on him. Ironically, multiple tabloids said that it was actually he who was doing the cheating.

Stories of bad behavior have surrounded Pettyfer for a while, which has caused his once-hot career to cool down considerably. Under the circumstances, it might be a good thing for Agron that the relationship didn't work out.

Friends: Anna Popplewell and William Moseley (The Chronicles of Narnia)

Peter and Susan looking at something in the distance.

Rumors have a way of taking on a life of their own. Such was the case with two young stars from the Chronicles of Narnia franchise.

Anna Popplewell plays Susan Pensevie, and William Moseley plays her brother Peter. In a rather uncomfortable bit of speculation, there were reports that the onscreen siblings were dating in real life. Truthfully, the two were never together in that sense, although they did build up a close friendship over the course of making three movies.

Moseley was asked point blank if he was dating his co-star by the website ONTD, and his response was, “Uh, no, we’re just sisters I’m afraid, brother and sister, siblings.” In 2012, the actor also tweeted out a photo of her with the caption “Happy Birthday to my surrogate sister Anna Popplewell!”

Dated: Anna Camp and Skylar Astin (Pitch Perfect)

Anna Camp and Skylar Astin

The Pitch Perfect movies have all been solid box office performers. Behind-the-scenes, the franchise is responsible for an aca-awesome love story between Anna Camp, who plays uptight Aubrey, and Skylar Astin, who plays Jesse.

The couple met on the set of the 2012 original and immediately started making waves. "We were friends first and just hit it off, " she told Glamour magazine.

She was divorced, hesitant about getting into a new relationship, and five years older than he was, but the chemistry was undeniable.

Astin had no reluctance whatsoever, telling Popsugar that "I knew the second I met her that I wanted to know her, and I just wanted to be in her life. "

Camp and Astin got engaged in January 2016. In September of that same year, they tied the knot. They've been happily married ever since.

Dated: Jamie Campbell Bower and Lily Collins (Mortal Instruments)

Jamie Campbell Bower and Lily Collins

Here's a celebrity couple who dated, broke up, got back together again, broke up a second time, and might possibly be back together once more.

Jamie Campbell Bower and Lily Collins starred together in Mortal Instruments: City of Bones in 2013. They began dating on the set, but broke up right before it hit theaters. Both dated other people afterward.

Then, in 2015, they reunited in London and rekindled the relationship. "Sometimes it just is what it is... And what it is, is something quite beautiful..." Collins wrote on social media. A while later, the affair was over for the second time.

In early 2018, there was speculation that they were back on, after the two started liking each other's Instagram posts. It seems they can't quit each other.

Friends: Shailene Woodley and Miles Teller (Divergent)

Shailene Woodley and Miles Teller worked together in the Divergent series, but they met on the set of a different film, the teen drama The Spectacular Now. Since then, a really charming friendship has blossomed between them.

The actors' paths repeatedly cross, which serves as a sign of the high level of respect they have for each other. When Woodley received an award at the Sundance Film Festival in 2013, Teller was the one there presenting it to her. He did the same thing when she won the Trailblazer Award at the MTV Movie Awards. They were once jointly nominated for Best Kiss at that same ceremony.

The admiration goes the other way, too. Woodley told W magazine, "I would love for us to be a famous screen couple, like Kate Winslet and Leonardo DiCaprio."

Dated: Evanna Lynch and Robbie Jarvis (Harry Potter)

Evanna Lynch and Robbie Jarvis

Evanna Lynch and Robbie Jarvis met during production of Harry Potter and the Order of the Phoenix in 2007.

Lynch portrayed Luna Lovegood, and Jarvis was the teenage iteration of Harry's dad, James Potter.

Fans got to keep tabs on the romance, thanks to a shared penchant for frequently posting pictures of themselves on their Instagram accounts. Among the more interesting tidbits from their relationship is that she got him to give up eating meat and embrace a vegan lifestyle.

Although they appeared happy in their pictures together, there were obviously elements that weren't working. At the 2016 premiere of the Potter spinoff Fantastic Beasts and Where To Find Them, Lynch confirmed to US Weekly magazine that the pair were no longer romantically involved, but were “still friends.”

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Which of these YA couples who dated is your favorite? Which one of these friendships do you like most? Give us your thoughts in the comments.