While this is a simplistic view, I can agree with the aspects listed... each instance is different. Cheating can be as simple as being horny and opportunistic, or peppered with feelings of neglect/resent/boredom/feeling trapped, etc. etc.

Although, one thing I do disagree with is saying that the person being cheated on is the problem. Regardless of relationship issues, people should respect their SO enough to at least end the relationship before seeking thrills through someone else.