was never a healthy act or should be there. Once you are with a partner, then I guess there is no excuse to cheat on him/her. If there is a problem, just try to talk about it, but come later [after getting caught cheating] to say that I did it because of this and that??

Sorry but not an excuse, be open with your partner and if you had to hurt her/him about something going wrong then it is better than letting them feel the pain of being cheated on and maybe lose your relation forever while your intentions was none of that.

Do not dwell in the past, do not dream of the future, concentrate the mind on the present moment. (Gautama Buddha)