What's Your Number? (2011)

Ally is a woman who has many ex-boyfriends who turned out to be losers. Now she believes that she can't find a good guy. But when she runs into one of her exes who is now a 'Prince Charming', she decides to look up all of her exes to see if any of them have changed for the better. And when she has trouble locating them, she asks her neighbor Colin, who sleeps with women every night and sneaks out the morning after to avoid talking to them, to help her.