Jessie breaks off her third engagement because it doesn't feel right and now she wants to avoid relationships until she meets "the right one". Meanwhile, Aiden has made a bet with his poker buddies at work that he can find a girl and marry her before Christmas in four weeks. At an vernissage, he meets Jessie and decides that she is the one he should try to win.
The story is really questionable on so many levels. It's the whole concept of the movie that feels wrong.
SPOILER ALERT: That Aiden blows off the bet is okay, but that they still get married after a few weeks feels really weird.