I only helped cheating. I have shared the bed with... 3 women who where married now (two were with the husbands consent). And with 2 girls who had boyfriends. Neither with consent. I don't feel bad about it I mean, I'm technically not cheating and what someone else does with his/her life that's up to them.
The women who had their husbands consent were by the way married longer and a lot happier then the one I had an affair with for over a year. I read about it yesterday, a new phenomonon called Polyamorie. Having multiple lovers with eachothers consent. Apparantly it strengthens the bond if you are not the type to claim or be jealous and I kinda feel that way as well. I'm not jealous and during the time that I still had "free relationships" I didn't care what my girls would do while I wasn't with them. I kinda enjoyed their stories too, they were educational.
So to answer your question Nightwish, I don't think it's cheating even if one of m has sex- as long as the other party knows what is happening.
The Doctor will see you now Promoting Lesbianism -->