OK so my Girl Friend, Kate, and I have been dating for a year now. We have yet to have sex, And I'm 100% in love with her. She always said how she was bi-sexual but the most she had ever done was kiss another girl. Come the 8th month mark her best friend, her sister basically, Sharron, came over. I always told her how I thought it would to be awesome to see them go at it. So she calls me up and says that they were just having sex and for a little bit do to my damn guy hormones I thought it was AWESOME! But then it hit me that I honestly wasn't OK with it. So I tell her that I'm not OK with it and she says "OK". So a couple days later (Sharron was staying over there for over a week) I text her and she says "I'll text you in a few we're about to do it." And I flat out tell her no but she does it any way. I had to keep telling her that I wasn't OK with it and I had to catch her 2 more times. Those times they didn't do any thing. And then I keep begging her not to do it any more and she starts yelling at me, saying "I only did it for you!" To where I replied "If you were to do anything you wouldn't cheat on me like that." I just want to ask what should I do? I keep having to ask her every time she's over there not to do anything! Is it really cheating? And what should I do about her when I honestly can't trust her to just be around her with out cheating on me! I need some help on what to do with her. And honestly with all this I'm seriously questioning if she loves me.

Ok is she her best friend or her sister? If they are best friends I can take this one way. If they are sisters I may have to walk away from this one.

But for some reason I see this as a game. How old are you? I guess either the way you wrote it or how I am reading it I see it as some sick game of hers. Have you actually caught them? Or are you just going on her word? If your just going on her word I almost think she is instigating you. Is it worth the effort?

I'm guessing they're friends,not actually sisters?

Mindgames?

Why bother?

Yes, she is cheating.

For a year the two of you have been a couple, in a relationship. That means two people, not three.

She has openly been having sex with her friend, female, and that makes her a cheater.

It doesn't matter if she is cheating with a male or a female. Or if the two of you were a gay couple or a straight couple. Cheating is cheating.

That she told you in the beginning she was bi, does not excuse her, or justify, having sex with any other person, male or female.

If she wants it both ways, she should be dating, not in a long term relationship with you.

Doesn't matter why she cheats, or with whom, what matters is she did. Get your feelings out of the way, and deal with the cheating and not by begging her not to.