Sexually frustrated virgin meets older bad-boy potential brother-in-law

How come I haven't seen this film before?! I loved Adam Scott in "Parks & Recreation", and he and Brittany Snow used to play comedy roles; so this film kinda caught me 'off guard'.

NOT SPOILERS ⤵ 

I loved this film, because it's crazy and unpredictable! Or crazily unpredictable! For most part of the film, the actors are portraying such odd characters you'd think they suffer from mental problems (which they probably do, if you count insomnia and anxiety as mental issues).
Indie or not, I enjoyed this film not only because of the plot, but also because of the plot twists. Asked myself more than once: "What the hell is (s)he doing?!". I like that about films!
THAT SEX SCENE, THOUGH!  I'd been waiting for THAT scene the whole film! Was it just me, or Adam Scott emanated sexual cue and tension, despite looking scruffy and hurt?

Questions now:
Was Emma REALLY a half-virgin when she... ?

Are there any other films with similar plot i.e. person comes into lover's household, meets relative and has adultery sex with them?

THANKS!