4. Closer (2004)
Mike Nichols' 2004 drama, credited with helping Clive Owen rise to fame, can also be credited with causing your courtship to go down in flames if you're nuts enough to entertain the idea of renting this with your boo. Ever.
Inspired by Patrick Marber's play of the same name, Closer trails two intertwining couples, both of which spend the duration of the movie having affairs with each other, tearing their partners apart, lying through their teeth, and switching back again. With the cheating rate reported to be as high as 70% for dudes and 50% to 60% for women as of 2011, does it seem like any non-awkward conversation can possibly follow this flick?