I understand where you're coming from. I have cheated on girlfriends in the past only to feel miserable about it in the aftermath. The best thing i can say to you is that, if there is a need or feeling to wanting to cheat or being enticed by someone of the opposite sex, while you have a gf/bf should be a clear answer as to your feelings of the person your dating. What i mean is when you find your soulmate or the person you are meant to be with, then other memebers of the opposite sex will not entrigue you or entice you anymore. Thats just my opinion and what has happened to me since I met my current gf and its the greatest feeling.