People get married or have monogamous relationships to have their needs met for physical intimacy. Sometimes those needs change and partners can't get through it because of a lack of communication or lack of understanding the problem. Then some men and women are just dogs. Why not just split up? Children, finances, what other people would think. There are lots of reasons not to split up. My wife entered menopause in her mid 30s. We went from having sex 3 to 5 times a week to once every 8 to 10 weeks. I need more than that, my wife has the attitude that this is how it is going to be and that I should get used to it. To me, that is unacceptable. So I have cheated. If she cheated, it would be a different story, she shouldn't share what she isn't giving me. If I left her, she couldn't make it by herself at this time, so I stay. In a year or so, that may be different, if it is, then I will move along on my own. There is a whole lot more than just cheating in some cases.