The relationship of Chandler and Monica for the first few seasons more of friendship showing some crushes but nothing big. Such as the time Chandler said that if Monica is not married at 40 they will get married. Prior to Monica and Chandler officially becoming a couple, throughout seasons 1-4, Chandler and Monica are occasionally seen sitting very close or sitting in a chair together. In the end of season 3, at the beach, Chandler does much to figure out why Monica doesn't think he'd be a good boyfriend for her.
Their actual relationship starts when Monica becomes depressed at the rehearsal dinner for Ross and Emily's wedding: her brother is getting married for the second time while she doesn't even have a boyfriend, her mother keeps making cracks suggesting she'll never get married and some drunk guy thought she was Ross' mother ("The One With Ross's Wedding, Part 2"). She decides that maybe a night of meaningless sex will make her feel better and goes looking for Joey. He isn't there, but Chandler is, and when Chandler attempts to console her, telling her he thought she was the most beautiful woman in the room that night, that she was the most beautiful woman in most rooms, Monica throws herself at him and they end up spending the night together. The next day, initially things are quite awkward between them. When they meet up at the wedding they agree that sleeping together was a stupid thing to do, but that's not enough to keep them from agreeing to meet up again that night. Although they go on to fall in love and have the longest romantic relationship between two of the friends throughout the series, it's not clear at this point how much of their relationship is based on genuine feelings and how much is just about sex. However, in The One With The Truth About London, Chandler refers to the first night he and Monica spent together as the most romantic night of his life, so it seems likely that Chandler, at least, already had romantic feelings for Monica by the time their first night together was over.
They try to keep their relationship secret from their other friends but they all eventually found out. Joey finds out when he realizes that the two took a trip together ("The One With The Kips"). Rachel overhears a telephone conversation between the two containing sexual innuendo ("The One With All The Resolutions"), although Monica denies this when she is confronted by Rachel ("The One With Chandler's Work Laugh"). Phoebe finds out about Monica and Chandler when she and Rachel go with Ross to check out Ugly Naked Guy's apartment and, looking through the window towards Monica's apartment, she sees the two of them having sex together. Ross finds out the same way in the last scene of the same episode. ("The One Where Everybody Finds Out")
When they all go to Vegas, they're on a winning streak at the craps table when Chandler tells Monica that, if she rolls another hard eight, they should take it as a sign and get married that night. One of the dice comes up with t four and the other rolls off the table. When they go looking for it, they see it could be either a four or a five, but they agree that it's a four and decide to get married. They go to a nearby wedding chapel and are waiting to get married when a very drunk and married Rachel and Ross emerge from the wedding chapel ("The One In Vegas, Part 2"). Seeing Rachel and Ross's disturbs both Monica and Chandler, and they start to think they're moving too fast. They each want to back out on the Vegas wedding, but neither of them wants to disappoint the other, so they decide they're going to leave it up to fate. However, even though they keep getting signs telling them they should get married, they decide they aren't ready yet, but they decide they want to live together instead ("The One After Vegas").
A year later, Chandler decides he's ready to propose to Monica and he takes her out to her favorite restaurant for a romantic evening. However, the evening doesn't go as planned; Richard shows up and is seated at the next table. When they get home, still not engaged, but first Phoebe and then Rachel ask to see Monica's hand, Chandler is upset believing his surprise has been ruined. Phoebe and Joey convince him it's not, that all he needs to do is take a couple of days convincing her that he's nowhere near ready to get married, then it will still be a surprise when he actually does propose. His plan goes off a little too well, and things get even more out of hand when Richard shows up and tells Monica he still loves her and wants to marry her. Monica is very upset about how unfair it is, saying that "fair" would have been if Richard had wanted to marry her back when she was still in love with him, or if Chandler wanted to marry her now. Meanwhile, Chandler frantically searches for her, worried that he'd gone too far in pretending he didn't want to get married and that he might have ruined everything. When he returns to their apartment that evening Joey had already explained everything to Monica, and she was there waiting for Chandler with hundreds of candles burning all over the room. Monica gets down on one knee and tries to propose, but she starts crying so much she can't finish it, so Chandler gets down on one knee as well and asks her to marry him. ("The One With The Proposal, Part 2")
In Season 7, the two planned how their wedding was supposed to be but unfortunately, her parents already spent her money for buying the beach house. ("The One With Rachel's Book") Chandler has saved exactly the amount they need for Monica's dream wedding but Chandler won't spend all of his savings on one day. But Monica wants the perfect wedding Chandler will spend all the money they have but Monica decides that she wants a future and not spend their security on the wedding. Chandler tried to bond with his future Father-In-Law during a close sauna encounter backfires ("The One With Phoebe's Cookies"). Monica's mom decided to get their wedding announced in the newspaper but Chandler was unphotogenic that he can't take a good picture with Monica ("The One With The Engagement Picture") . Joey decided that he would officiate their wedding and gets his minister certificate in the internet. Monica tells the story how they got together. Chandler finds out that Monica actually wanted to sleep with Joey when she knocked on the door but Chandler was the only one there. Chandler is really upset and doesn't want Joey to do the wedding anymore. Joey talks to him about how Chandler and Monica are meant for each other and nothing could take that away and Chandler is happy to let Joey do the wedding. ("The One With The Truth About London").
With four weeks left before the wedding, Chandler and Monica are faced with the issue of their wedding vows. With each person dealing with their own problems in writing the vows, they turn to memories of past events to help them. In the end, the only real problem is who will be saying the vows first.("The One With The Vows").
Ross makes everybody burst into laughter by threatening Chandler physically if he ever hurts his little sister. Chandler and Monica have their rehearsal dinner and after seeing his sexy celebrity mother and drag-queen dad, Chandler suddenly freaks out thinking about becoming "Mr. and Mrs Bing." He freaks out more when he hears the new answering machine message Monica recorded, so he writes a vague apology note and runs. Ross finds it and goes looking for Chandler while Phoebe and Rachel attempt to divert Monica, who is too wedding-high to notice soon anyway. Rachel and Phoebe find a positive pregnancy test in Monica's bathroom waste basket. ("The One With Monica And Chandler's Wedding, Part 1"). Ross, Phoebe and Rachel finds out that Chandler is missing, Rachel distracts Monica while the two found Chandler... in his office, the reason he was hiding because he is panicking to become the "Bings" Ross gets him to face things one at a time and he feels better. Later smoking in the hall, Chandler overhears the girls about Monica's pregnancy test, and instead of freaking out he gets her a present and decides a baby isn't too scary. After the ceremony, Monica denies having taken a pregnancy test, Rachel seems to know more. ("The One With Monica And Chandler's Wedding, Part 2")
In one important episode, Chandler learned that he would have to spend Christmas without Monica and the Friends in Tulsa, or else be fired from his job. He comes to feel empathy for the employees underneath him who are clearly depressed because they want to be spending Christmas with their families and tells them all to go home. After a female colleague named Wendy decides to stay behind to help him, Monica calls him to wish him a merry Christmas, and when he makes the mistake of mentioning that Wendy has stayed behind to help him, Monica gets suspicious and grills him, and he ends up inadvertently making it clear that he is attracted to Wendy, but assures Monica nothing will happen between them. When Wendy then hits on him, Chandler politely rejects her, saying he's a happily married man and nothing can happen between them because what he has with his wife is great. Wendy responds by asking him why he's spending Christmas with her instead of with his wife if what he has with his wife is so great. Realizing Wendy is right, Chandler decides he's had enough and quits his job before returning home to spend Christmas with Monica and the rest of the Friends, much to their delight. (The One With Christmas In Tulsa)
After a year of trying to conceive, Monica and Chandler are still unsuccessful. They go get fertility tests and find out that due to Chandler's low sperm count and Monica's inhospitable environment, that they will most likely not conceive children on their own. Saddened by this, Monica and Chandler resolve to find another way to have kids. ("The One With The Fertility Test"). With surrogacy rejected as Moica had always dreamed of carrying her own child, and donors ruled out because Monia didn't want to carry a baby that wasn't Chandler's, they decided to adopt.
In The One With The Late Thanksgiving Monica and Chandler receive a call from the adoption agency saying that they were chosen by a pregnant woman in Ohio, Erica. Although there was initially some confusion during the adoption process - Erica had confused Chandler and Monica's file with a couple who were a doctor and a reverend respectively -, Chandler eventually convinced Monica to admit the truth, subsequently winning Erica over despite the lie by convincing her that they had only lied because Monica so desperately wanted a child.
In the series finale, Erica gives birth, but she didn't know that she is actually pregnant with twins, she had misinterpreted the reference to two heartbeats as referring to her heart and the baby's. Chandler and Monica subsequently name the boy Jack Bing (after Monica's father) and the girl Erica Bing (after her birth mother).
- Their sexual relationship occurred accidentally.