Do you cheat on your GIRLFRIEND/BOYFRIEND?

I for one have to admit I have cheated on my girlfriend...I still can't figure it out why I did it , but I guess it had something to do with the girl I cheated on her with...she was very very pretty and my girlfriend and I at the time ... well.. we weren't getting along very well so it just happend. Call me a pig if you may , but I can't say I'm sorry I did it because I enjoyed it and so did my mistress :D , besides... things wil soon change between me and my girl..that's life , not always fair :|