Adultery was a storyline in a movie about the earliest North Americans. Zacharias Kunuk's three-hour Atanarjuat, the Fast Runner(2001), the first ever Inuit language fiction feature and the winner of the Camera d'Or at Cannes, dramatizes a popular myth of the first people of the Great White North involving adultery, rape, pillage, murder and eventual reconciliation.
Jungle Fever(1991) explored the inevitable adultery that occurs when a married African American man is left alone in an empty office with a white woman—or at least that's how I seem to recall Spike Lee explaining it. It's considered one of Lee's weaker films, but we can thank urban culture for the term "movie adultery," which means to betray someone by seeing a film you promised to see with them first.
America's moral police will be happy to know that movies coming out the rest of this year won't be focused as much on adultery. No, based on the just-concluded Sundance Film Festival, child rape—emotionally and/or physically—is what will soon be coming to a cineplex near you.