Like someone said before. You are seriously asking this question on a forum? Sad in my eyes. Women are human beings, they need to be treated as humans. I would say it depends on your situation. If your GF cheated on your and had intercourse with some other guy you dont know, then I would be very careful at what you are doing. But yea, if she is nice, and your GF doesnt have a problem with it, then why not? lol.