I have never cheated before, it is against everything i stand for. I despise cheats, contrary to my persona whereby i think casual sex is all well and good. I got cheated on before, with a girl i had known for 15 years and was in a relationship with for 2 years. I found out and i never spoke to her again, or have had any contact with her again, she is dead to me since 5 years ago. (with my former best mate, none the less) I would never get into a relationship unless i love the girl, a lot. If you get Vain into a relationship, chances are that I want to be with you for the long haul, even though i won't tell the girl obviously (in order to self-preserve/protect myself). I would not just go into a relationship with a girl if i was in love with her and/or sleeping with her either, it would have to be a very rationalised decision for me to choose a girl to 'commit' to. To date, since 5 years ago now, i have not been in a relationship, it is not worth the potential betrayal.
I have however, unknowingly, slept with girls who have had bf's, one night stands in university. If i knew they had bf's i would have serious reservations about sleeping with them. And i won't lie, i feel bad for it, not ashamed because they were the ones that knew and i didn't, but i just feel bad about it because that poor guy on the other end used to be me. Getting sex and relationships is so easy these days that the whole value of relationships overall has gone south.
I don't understand guys that are unable to get (and subsequently complain about being unable to get) one night stands and relationships when if you're anywhere resembling good looking you get inundated with offers/approach invitations all of the time in university. Even if you're not the coolest/best looking guy you could still get someone from your social circle/style , surely. Sex and relationships? Easy to get in England. I see not very good looking guys with attractive girls every day.
But committed relationships? I think you have to be very good looking, no doubt about that, you have to be someone who your girlfriend or boyfriend can't really do much better than, i.e. it would be very difficult to replace you. However, some people just like cheating anyway because it is an instinctive/exciting thing that they just feel a compulsion to do.