[Tomt] [movie] romance movies

The movie is about an author who has been turned off of men she thinks all men will eventually cheat. She writes a book where To avoid getting cheated on women should only date men for 6 months then breakup up. She has a sister who is a partner at a law firm. To prove her wrong the sister hires a junior colleague to seduce and date her to prove she’s wrong in turn he will become a partner. They eventually start dating. He tells her she is wrong and to prove her wrong he challenges her to a contest it involves her seducing but not having sex with certain married men who he has chosen within a certain time frame to prove she’s wrong seduced them she must procure their underwear. She eventually gets the first few and is to the last one but he hasn’t told her who yet she is anxious to Finnish the challenge so she chooses to seduce his friend and he walks in on them. He storms off and drinks. She is regretting her actions and goes to talk to her sister and finds out the guy and her sister dated in college eventually he shows up drunk and sad. And the sister decides to show that he wouldn’t cheat on her by attempting to seduce him he does not come on to her advances. And tells the sister about how much he loves the author woman. She hears all this and comes out and they kiss and reconcile. I don’t know the name of the movie