<human>: Long story short my girlfriend and I talked about having a threesome with a mutual friend (female) we discussed beforehand the boundaries and what we can and can't do. My only restriction was that whatever acts I performed on the other girl id also have to do on my girlfriend. Well last night we gave it a shot and it was pretty much the worst experience ive ever had. Not only was I not allowed to touch or do anything with the other girl but I was also cut out of the entire experience, I pretty much was forced by my girlfriend to just sit there and think only of her..she got pretty hot and heavy with the friend and they ended up taking it really far before I stopped them. I explained to my girlfriend in front of the friend our agreement and she got super mad and said I wasn't allowed to touch another girl and that she 'didnt remember agreeing to that' etc etc.

Now my male friends ive asked all argue that I was a pussy and should have just let them have sex, since I could of just watched but a huge part of me saw it as her cheating on me and me not being able to join in. Like she got a juicy steak and all I got to do is look through the window while she ate it.

The friend was very vocal about how she didn't mind and actually wanted me to join in, but my girlfriend started raving about me ruining the night and now shes giving me the silent treatment.

Some added info is that I have been 100% loyal to her through our entire relationship and she has cheated on me in the past with 2 guys which ive forgiven her for since it was early in the relationship. Im pretty sure unless someone in this thread changes my mind im going to end it with her. I think she's acting very selfish.

Can you condense the text into a few key points?
<bot>: Tried to have a threesome with set rules but when it happened gf didnt allow me to join in, got mad when I stopped her since I couldn't.