Like most series on the CW, Arrow has had its fair share of romantic relationships. All have had their ups and downs. Some were obviously temporary. Others were obviously meant to be endgame, so other love interests for those characters couldn't last.

Some had to happen so that the characters could move on to other relationships. A few were simply so that a character wasn't single or for some plot-related reason. Some were pleasant surprises that the series took the time to explore.

If fans are going to care about characters, they need to see these characters' relationships, specifically romantic ones.

A relationship can hurt a show because of what it does to the characters involved. In at least one case, a character sided with the wrong person and didn't think about what really mattered. It's also a problem when a relationship that's clearly not going to last takes up a lot of screen time, especially looking back. With at least one, the problem was that one character was with two people from the same family.

Then there's chemistry. If there isn't any between two actors, there's nothing that can be done. Fortunately, in one case, not only was the chemistry there, but the writing was as well. The fact that Arrow went with what worked on screen and not in the comics made the series better.

Two characters may not have made a good couple, but without their relationship, another character wouldn't exist. That made that relationship worth it.

Here are 10 Couples That Hurt Arrow (And 10 That Saved It).

Hurt: Oliver and Laurel

Oliver and Laurel are the Green Arrow and the Black Canary and are together in the comics. However, Arrow saddled them with a horrible history, and the actors had no chemistry.

Before the series began, Oliver took his girlfriend Laurel's sister on a boat trip. He returned, but Sara didn't.

When Laurel saw him again, she told him that it should have been him who didn't return.

She still had feelings for him, as Tommy, Oliver's best friend and her boyfriend, knew.

Love triangles tend to hurt a show, as this one did.

Tommy saw Oliver and Laurel together, through her window, from the street.

While Arrow never returned to that relationship, it was the wrong move to have Laurel tell Oliver he was the love of her life (and she knew she wasn't his) in her final moments.

Saved: Diggle and Lyla

Before the series began, Diggle and Lyla had been together and married. However, they didn't work out that time.

They reconnected while Diggle was still going after the man he thought took his brother's life. He even went to Russia and got himself arrested to free her from prison.

They had a baby— baby Sara, who became JJ because of Flashpoint— and got remarried.

They're not always on the same page when it comes to their jobs and ARGUS. However, since their reconciliation, they've been the most stable relationship on the show.

The only downside is that Lyla's not around nearly enough. The series would be better with more of this relationship and more of her.

Hurt: Felicity and Billy

Arrow never bothered to show anything more than it needed to of Felicity and Billy's relationship.

This relationship was more about Oliver than Felicity. He needed to be able to date Susan without looking like the bad guy for dating someone first. (It was his lie that ended his and Felicity's engagement.)

Oliver also needed to accidentally take Billy's life so that he could feel bad about it after. (Everyone comforted him, but not Felicity, as she was the one who lost her boyfriend.)

The series never showed how Felicity and Billy met. It also didn't explain why she dated him when she knew that Oliver was waiting for her to be ready to talk about their relationship.

Saved: Thea and Roy

Theirs wasn't exactly a meet-cute. He stole her bag. However, they were good for each other and good together because they were opposites. She was the rich girl and he was the boy from the bad part of town.

Though they were on-again/off-again, and when both actors were series regulars, they were each other's best relationship.

After Roy left, Thea tried to move on, with two equally bad (and bland) love interests.

They found their way back to each other (though not necessarily in a romantic way) whenever he returned. After Oliver found happiness with and married Felicity, he wanted the same for his sister and pushed Thea to be with the person who made her happy: Roy.

Hurt: Oliver and Isabel

The problem here isn't that Isabel was a villain working for Slade Wilson in season 2. It wasn't that she took Oliver's family's company from him. It wasn't even her attitude toward Felicity as she left Oliver's hotel room in Russia.

It was the fact that Isabel had been involved with Oliver's father and called Robert her soulmate. Not only that, but according to her, Robert was going to leave his family for her.

Instead, he changed his mind and terminated her internship when Thea got hurt.

While Oliver did not know this before he was with her, she did. Choice of significant others is one area where "like father, like son" should not apply.

Saved: Moira and Walter

None of Moira's relationships were exactly the best. Robert was unfaithful to he,  Malcolm was never really a relationship, and she didn't treat Walter the best (just look at his kidnapping in season 1).

Having her be remarried when Oliver returned was a good way to show how things had changed while he was gone in a positive way.

Walter wasn't some evil guy seeking to hurt his family. He was a stabilizing presence for Moira and for the company.

Also, it was because of her relationship with Walter that he became part of Oliver and Thea's lives. He had a positive impact on and helped both of them.

It's a shame that he hasn't been seen in years.

Hurt: Thea and Alex

On the one hand, at least Thea's last relationship before Roy's return wasn't with Chase the DJ. On the other hand, Alex was a really bland character, even before H.I.V.E.'s mind control pills. Thea deserved so much better.

There was never anything special about their relationship.

He was just there and they were just together. Then he was gone and they were over. It wasn't even clear if he had lost his life or if he was just unconscious during his last appearance on the show.

It seems like the show forgot that he— and this relationship— existed even when he was still around. There was no point to Thea dating him other than to show her with someone other than Roy.

Saved: Felicity and Barry

Felicity and Barry were never really more than a possibility on Arrow. Their one kiss happened on The Flash, though they knew that they were not meant to be.

They both had other people they cared about but couldn't be with at the time (Oliver for Felicity, Iris for Barry).

Still, bringing Barry onto the Arrow and setting him up as someone in Felicity's orbit was a smart move. It allowed the show to explore her relationship with someone outside of the team in season 2.

Oliver and Felicity were still almost a season away from their first date. However, bringing in Barry added a layer of tension to their relationship that was fun to watch play out on screen.

Hurt: Diggle and Carly

It wasn't the worst thing that Diggle dated his brother's ex, but the relationship could have been handled better.

At the time, Diggle didn't know his brother was alive, and he did struggle with dating Carly. However, it could not have lasted simply because it turned out that Andy was alive and did return in season 4.

If Arrow had decided to stick with Diggle and Carly, that would have meant more drama.

Diggle and Carly's relationship ended off-screen between seasons 1 and 2. That should say it all.

The series moved rather quickly (back) to Diggle and Lyla, and Carly hasn't been seen since. Any time spent on Diggle and Carly was really just a waste looking back on it.

Saved: Oliver and Sara

The way that Oliver and Sara started wasn't the best. He was her sister's boyfriend, but that didn't stop her from going on a boat trip with him. This hurt the planned main relationship before the series even began.

However, having Oliver and Sara give things a try when she returned to Starling City in season 2 wasn't a bad move.

Sure, they never would have lasted. They both had other people in their lives they cared about.

Putting them together did give Arrow the chance to explore a relationship featuring the Arrow and a Canary.

They both had been through hard times in their years away, and they worked well together in the field.

Hurt: Quentin Lance and Donna Smoak

This relationship wasn't one of CW's worst. Lance and Donna just so happened to meet when she was in town visiting Felicity in one episode.

After everything he'd been through (and would then go through), he deserved some romance in his life.

However, their relationship could have been handled better.

Season 4 ended with them still together, and they even left Star City together. When season 5 began, they'd broken up off-screen and that was it.

Then, in season 6, they danced at Oliver and Felicity's wedding but were interrupted when Oliver's lawyer called.

The series never addressed their relationship again before Diaz ended his life. Maybe if it had, the time spent on them would have been worth it.

Saved: Laurel and Tommy

Because of the comics, it was supposed to be Oliver and Laurel together. However, in his five years away from Starling City, she got together with his best friend, Tommy.

Even with a love triangle, which is rarely good for a show, Laurel and Tommy were good together. It helped that the actors had chemistry.

If not for Oliver's presence and his and Laurel's history, Laurel and Tommy could have worked out. This would have been best for her character as well. He lost his life trying to save her during the Undertaking in season 1.

Since the series never bothered returning to Oliver and Laurel's relationship after season 1, she and Tommy deserved better.

If the series had focused on them instead of circling back to Oliver the way that it did, it would have been better for it.

Hurt: Thea and Chase

Chase the DJ was easily one of the worst characters ever on Arrow. When he was first introduced, he thought he was too good to have to audition to DJ at Verdant.

Then it turned out he was a member of the League of Assassins, which could have made him more interesting-- but it did not.

He tried to end Thea's life by adding poison to her wine, but this attempt resulted in him losing his life.

There was no way that Thea and Roy weren't going to get back together, so Chase was obviously temporary.

After he was gone, all he became good for was Thea's remark at Oliver and Felicity's wedding reception that she doesn't "do DJs."

Saved: Oliver and McKenna

There weren't many people from Oliver's life before the island (and Hong Kong and Russia) with whom he reconnected.

He and McKenna never would have worked out. He was the Hood and she was a cop. He would never have told her his secret.

It didn't help that the series clearly had plans to return to Oliver and Laurel's relationship that same season.

However, while they were together, it was a nice break from the Oliver/Laurel/Tommy love triangle.

McKenna was someone normal he could be with (temporarily). It never felt like a relationship that was forced or one that would last too long.

It was good to see him try to be with someone other than Laurel.

Hurt: Dinah and Vince

Dinah and Vince could have been a good relationship. They could have been two people who fans wanted to see have a happily ever after. After all, she was surprised to find out he was alive, and he wasn't actually a villain.

The problem started when Vigilante turned out to be Vince because Vigilante was introduced before Dinah in season 5. Vigilante was supposed to be someone who fans recognized, but he wasn't.

Then, the show shoved as much of their relationship as it could into only a few episodes before Black Siren took his life.

Dinah then became so consumed with revenge that she and the newbies forgot that they were supposed to care about the city.

Saved: Moira and Malcolm

Moira and Malcolm were not a good couple by any means. They were not even really a couple, according to the definition of the word.

They were terrible together and to each other. He threatened her and her family. Their relationship occurred years before the show even began.

However, if they had never been together, Thea never would have been born.

This makes them a couple that saved the show because the series would not have been the same without her.

Willa Holland may no longer be a series regular, but Thea is still Oliver's sister, someone who knew him before the island and, more importantly, alive.

Before he knew about William, she was his only living blood relative.

Hurt: Oliver and Susan

Something that hurt Arrow significantly was making Susan a love interest for Oliver in season 5. She was introduced as an antagonist for Thea, but that became secondary to her dating Oliver.

Susan was a reporter investigating Oliver. She had a private investigator gathering information on him.

When Thea and Felicity learned that she knew he was the Green Arrow, they set out to make sure she couldn't use this information. Somehow, they ended up being the bad guys when they were simply protecting his and everyone's secrets.

Oliver even asked Felicity, his ex-fiancée at the time, to help him fix things with Susan after she was fired.

It's still unbelievable that Arrow put Oliver on the opposite side of his sister during this storyline.

Saved: Sara and Nyssa

Having Sara and Nyssa be together added another layer to the former's time in the League of Assassins. It also gave Nyssa ties to the team, especially after they lost Sara and while Ra's al Ghul was their enemy.

The best part about their relationship was that Arrow never acted like it was a big deal that Sara had had a relationship with a woman— because it wasn't.

Sadly, there was still so much more to their relationship that could have been explored. For the most part, it was all off-screen and before both characters' introductions.

While both have moved on— Sara to time traveling and a new relationship and Nyssa on her own mission— putting them together was a bold move and the right one for the characters and the Arrowverse.

Hurt: Black Siren and Diaz

Arrow never explained why Black Siren and Diaz had a (brief) romantic relationship other than… both of them were villains. Was it so that when she turned on him in the finale, it would be more surprising?

When they first kissed, it was one way to show that Black Siren was still evil.

This was when Lance was hoping to see something good in his daughter's doppëlganger.

Diaz then showed off their relationship in front of Lance later on, but this made it about Diaz showing off his power over him, not about Black Siren or their relationship.

It just got worse when Diaz called her "kiddo" when they were still together. That's pretty much the opposite of a term of endearment.

Saved: Oliver and Felicity

From their first scene together, Stephen Amell and Emily Bett Rickards' chemistry sparked. It took three seasons for them to get together, and they've had their ups and downs.

However, having them get together and get married was one of the best decisions for Arrow.

It has been a delight to watch them fall in love, especially since it was unexpected. They have shown how much they support and believe in each other over the years.

In season 6, they were one of the most stable parts of the show.

At a time when everyone— Curtis, Rene, Dinah and even Diggle— turned on Oliver, Felicity was on his side, even when he kicked her off the team.

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Can you think of any other couples that hurt or saved Arrow? Let us know in the comments!