In an episode of The L Word, a group of friends sit around a campfire and debate what counts as cheating. "Who here, put up your hand, thinks that kissing is cheating?" one of the women asks. Just about everyone raises their hand. Before that, one of the more conservative women in the group, Tasha, claimed that even thinking about having sex with someone outside of a monogamous relationship counts as cheating. That argument didn't go over well. As many of the other women say, it's hard to control your thoughts. But, there are people like Tasha, who believe that straying in your mind constitutes infidelity. There are also people like Shane, another woman in the group, who says that having sex with someone else might not be cheating if there isn't an emotional connection.
While this scene doesn't actually clear up what counts as cheating, it does make clear that there's no consensus on infidelity. For most people in a monogamous relationship, having sex with or kissing someone who isn't your partner definitely counts as cheating. But what about fantasising about a friend or acquaintance? Or lying about how much money you spend?