Monica and Chandler are possibly the cutest couple in Friends - they don't have the on-again, off-again that Ross and Rachel go through, they have a long history (unlike Mike and Phoebe), and they end the series with an incredible future ahead of them. And while they may not have realized that there was something between them until London, the signs that they are actually soulmates have been there all along.
From the very beginning, these two Friends had a very special connection, and from their earliest season to their actual wedding, relationship, and beyond, Monica and Chandler were always endgame. Not sure if you can see it? These episodes prove they were always meant to be together.
The One With Pheobe's Husband (S2, E4)
This isn't a particularly huge episode for Monica and Chandler, but they have an interaction here that is one of the earliest moments that fans start to realize how close they are. When Phoebe reveals that she is married, Monica gets upset that she didn't know - and this starts a chain reaction of people revealing each other's deep dark secrets. One of the best moments, though, is realizing that Monica and Chandler already knew each others - whether it's the underwear on the telephone wire or the third nipple.
The One At The Beach (S3, E25)
The season three finale and the season four premiere (The One With The Jellyfish) both work as a great moment to prove that Monica and Chandler were always meant to be together. In this double-decker episode, Chandler is trying to convince Monica that he would be a good boyfriend for her (not particularly seriously), and ends up letting it go after he pees on her when she is stung by a jellyfish. This isn't just a fun episode to look back on, knowing that they end up together, but a sign that they were always thinking about the possibility, and that they were always making each other laugh - not to mention being willing to do anything to help each other out.
The One Where Phoebe Hates PBS (S5 E4)
By season five, Monica and Chandler are together, but no one knows about it yet... which leads to some hilarity, when Rachel thinks Monica has a 'secret boyfriend' and talks about him in front of Chandler - inadvertently revealing that Monica called him 'the best she ever had'.
This leads to a lot of hilarity (and a brilliant dance on the coffee table), but it's the end of the episode that really makes this sweet. Here, Chandler apologizes, and tells her that 'If I'm the best, it's only because you make me the best'. He may be talking about sex, but it's true for their relationship as a whole.
The One With All The Thanksgivings (S5 E8)
Monica and Chandler's history stretches back to her high school days, when Chandler was Ross's college roommate and she and Rachel were best friends. This episode covers some of their earliest interactions in flashback, with Monica attracted to Chandler from the first time that she meets him. Of course, Chandler doesn't feel the same until the next year, after Monica has lost a lot of weight... a story that ends with him losing a toe! While both these flashbacks show that there has always been something between these two, the really sweet moment is at the end, when Monica shows she would do anything for him - to the point that she literally puts a raw turkey on her head and dances around just to make him feel better.
The One Where Everybody Finds Out (S5, E14)
Monica and Chandler manage to keep their burgeoning relationship a secret for an impressively long time, but this episode is where it all comes out - and in true Friends style, it has to involve some ridiculousness. In order to try and force Monica and Chandler to admit their relationship, Joey, Rachel, and Phoebe concoct a plan to have Phoebe 'seduce' Chandler. Of course, it actually ends with Chandler bursting out that he can't, because he loves Monica - but his willingness to even go along with it in the first place shows how far he would go to make sure she is comfortable.
The One With The Joke (S6, E12)
This episode includes one of the sweetest lines between Chandler and Monica (and that's saying something), after Phoebe insults her by calling her 'high maintenance'. Monica is offended at this, and ropes Chandler in to loudly proclaim in front of Phoebe and Rachel that Monica is extremely easy going. Of course, it's not particularly true, but after he finishes his pre-prepared speech, he tells her "You’re not easy-going, but you’re passionate, and that’s good. And when you get upset about the little things, I think that I’m pretty good about making you feel better about that. And that’s good too. So, they can say that you’re high maintenance, but it’s okay, because I like…maintaining you."
The One With The Proposal (S6, E24)
This double-length episode is all about Monica and Chandler taking the next step - and it's one of the most iconic proposals in sitcom history. At first, it seems like it's going to be straightforward, with Chandler popping the question at dinner, but when Richard re-appears (and tells Monica he wants her back) things get complicated!
In the end, though, they propose to each other, Chandler finishing when Monica is too overwhelmed to, in their apartment filled with candles. It's sweet, romantic, and perfect for them both.
The One Where Joey Tells Rachel (S8, Ep16)
Monica and Chandler's relationship isn't the focus of this episode, as that goes to Joey and Rachel - but they do have a side story because Phoebe has met a man that she thinks is Monica's soulmate. Chandler does get jealous, as they talk about their love of cheese and building a house of it... but in the end, when Chandler tells her that he is upset and that she probably thinks he's not her soulmate, she tells him that she doesn't believe in soulmates, just like him.
The One With Monica And Chandler's Wedding (S7, Ep 23/24)
Where would this list be without the double-length episode where Monica and Chandler are getting married, and absolutely everything seems to be going wrong? In the end, though, it's clear they are meant to be together. Not just because they manage to overcome everything from a Greek Orthodox minister to Chandler's fear about becoming The Bings, but because Chandler says that he knew he wanted to be married the moment he saw her walking down the aisle - and because when he thought she was pregnant, he was actually happy, not freaked out.
The One With The Birth Mother (S10, E9)
There are so many moments in the final season that prove how perfect Monica and Chandler are for each other, but the episode where they meet Erica may be the best one. Here, they are trying to adopt, and end up meeting Erica... but find out it's a mix up, and she thinks they are someone else. In the end, it's Chandler who convinces Erica, just by being completely honest about how incredible Monica is. How much they love each other, and how great they are together, just shines through every scene.