No Strings Attached (2011)

A guy and girl try to keep their relationship strictly physical, but it's not long before they learn that they want something more. - IMDb Editor

Occasionally in the 15 years since summer camp, Adam and Emma cross paths. When he discovers that an ex-girlfriend is living with his dad, he gets drunk, calls every woman in his cell phone contact list, and ends up passed out naked in her living room. By this time, she's a medical resident in L.A. and he's a gopher on a "Glee"-like TV series, hoping to be a writer. She guards her emotions (calling her father's funeral "a thing"), so after a quick shag in the moments she has before leaving for the hospital, she asks if he wants a no-strings-attached, sex-only relationship, without romance or complications. A prescription for fun or for disaster?

Adam (Ashton Kutcher) and Emma (Natalie Portman) met each other once at a school summer camp but never committed. Several years later and they meet again. Adam is now a writer and an assistant on a TV show and she's a doctor. When Adam discovers that his father Alvin (Kevin Kline), a washed-up actor, is having a relationship with his ex-girlfriend, he goes on an all-night bender. Waking up in Emma's house, he finds comfort in her and they have spontaneous sex too. They decide that they should restrict their relationship to this level as she isn't comfortable with dating. She decides to keep it a secret from her housemate's Patrice (Greta Gerwig) and Shira (Mindy Kaling). Typically, Adam feels left out by this demand and tries to develop the relationship into something more with the help of his friends Wallace (Ludacris) and Eli (Jake M. Johnson). - Biggest_Loser

Handsome, charming Adam never forgot about Emma, whom he met at summer camp, and bumps into now he's a TV show assistant aspiring a script writing career and she a hospital intern. Utterly drunk after another depressing stunt form his terribly selfish father, twice-divorced Hollywood has been Alvin, Adam is carried to her med students apartment, waking up naked and taunted being oblivious, yet a good and apologetic sport. Emma admits being incapable of any relationship but he accepts to become sex mates without strings, which works a while, rendering her flirtatious best mate Sam jealous, while their other friends try to coach the non-couple into becoming one. Irresistible Adam does everything right, yet her fear of romance keeps spoiling the fun of his date plans. - KGF Vissers