Seth Winnick (Stewart) is on the way to his wedding to Chelsea Turner (Wilson) when his buddy and best man Larry (Bellamy) pulls him into the airplane bathroom for a little chat - in which he begs Seth to call off the wedding.
Flash back a year prior to when Seth met Chelsea, at Larry's own wedding to her best friend Holly (Banks). Chelsea is an interior decorator whose beauty immediately catches Seth's eye, while Chelsea herself is attracted to Seth because he's a nice guy who happens to be single. The two ditch their dates and hook up that very day.
Before long, Chelsea has moved firmly into Seth's life as his live-in girlfriend. She's funny, sexy, and drop dead gorgeous, seemingly everything Seth could want - and is making increasingly not-so-subtle hints that she'd like to marry him. She doesn't take it very well when he makes it clear to her that he's really not interested in marriage, and the relationship quickly goes downhill when she decides to sue him for palimony.
This film contains examples of the following tropes:
- Also sprach Zarathustra: Chelsea walks down the aisle to this.
- Black Best Friend: A twofer; Larry for Seth, and his wife Holly for Chelsea.
- Elvis Impersonator: Serves as the pastor at Seth and Chelsea's wedding. Justified, as they're in Las Vegas and Seth is an Elvis fan.
- Escalating War: Seth and Chelsea's relationship turns into this, with each one playing increasingly cruel pranks on the other. Which comes back to bite Seth hard when Chelsea decides she has enough grounds to slap him with a restraining order, effectively kicking him out of his own home.
- Happily Married: Larry and Holly are quite happy together, even though the situation with their friends puts a brief strain on their relationship.
- Here We Go Again!: The film ends with Chelsea and Seth being escorted out of the chapel - she in handcuffs and he on a stretcher - each threatening to drag the other back to court. Larry resignedly remarks to Holly, "We need new friends."
- How We Got Here: Nearly the entire film is a flashback, as Larry tries to convince Seth not to go through with the marriage.
- Idiot Ball: Seth grabs it when, instead of immediately putting as much distance between himself and his psychotic ex-girlfriend as he possibly can once he drops The Reveal, he does a Happy Dance all around the chapel in celebration of his victory.
- I Lied: Seth. It turns out his proposal to Chelsea was an elaborate plan to get her to willingly move out and give up any legal claim to his home.
- I Want Grandkids: Chelsea tries to pass off the abundance of wedding memorabilia in her home as hints from her mother that she needs to settle down.
- I Wrote Our Story: Seth, who is the scriptwriter for a TV sitcom, begins basing his scripts on the events of his own life even as things with Chelsea begin to fall apart.
- Kick the Dog: Seth throwing Chelsea's cat off a bridge. Gracie doesn't actually get hurt because she's in a harness attached to a cord, but it's still a dick thing to do.
- Chelsea's no slouch either as she often takes advantage of Seth's cat allergy, such as when she brings Gracie to bed with her and deliberately brushes dander and loose fur in his direction.
- Large Ham: Seth frequently crosses into this territory.
- Manic Pixie Dream Girl: Chelsea seems like this for Seth at first, as she certainly makes his life more fun and exciting. But when he's not willing to completely let go of his old life and marry her, things go from dream to nightmare.
- My Biological Clock Is Ticking: Why Chelsea's so fixated on getting married.
- The Reveal: There was no need for Larry to persuade Seth to call off the wedding, because Seth never intended to go through with it anyway.
- Rule of Three: On their first date, Chelsea tells Seth that she has a rule in which she will not sleep with a man unless they've had three meals together.
- Single Woman Seeks Good Man: Apparently why Chelsea fell for Seth. Though she seems to have been more interested in the fact that he was single.
- The Thing That Would Not Leave: One of Seth's major problems with Chelsea after they break up - she technically lives in his house and refuses to move out.