Is lusting after someone – cheating?

To some people cheating is the result of actually sleeping with another person. Yet I sometimes feel that being emotionally involved with someone else is more unfaithful than just sleeping with someone just for the sex. I think most men will see that as an excuse, but I do not mean to reduce the fact that sleeping with someone is also cheating.

I would be far more upset with my partner if he was emotionally involved with someone than having a one night stand with a blonde bombshell who was begging for it!