I had a girlfriend who was always paranoid that I would cheat. The truth is, it was extremely unlikely that I ever would cheat. I had gone through hell to find a girlfriend and my feeling was, "I'm not screwing this up." I had intense loyalty to her. But she was always scared I would cheat. She would rant about it and I would be like, "Christ, relax, I'm not going to cheat." And she ended up being the one who cheated.

It makes me suspect that the one most afraid of getting cheated on is the one who's most prone to cheating.