Pushed to the breaking-up point after their latest "why can't you do this one little thing for me?" argument, art dealer Brooke (Jennifer Aniston) calls it quits with her boyfriend, Gary (Vince Vaughn), who hosts bus tours of Chicago. What follows is a series of remedies, war tactics, overtures and underminings suggested by the former couple's friends, confidantes and the occasional total stranger. When neither ex is willing to move out of the condo they share, the only solution is to continue living as hostile roommates until somebody caves.
But somewhere between protesting the pool table in the living room, the dirty clothes stacked in the kitchen cupboards and the sports played at sleep-killing volume in the middle of night, Brooke begins to realize that what she may be really fighting for isn't so much the place but the person.