<human>: This happened last month and yet it is still bothering me. We had only been together for a few weeks at the time, and I knew (because she had told me) that she found one of our mutual friends attractive. We were all hanging out together one day (as well as another friend who came with us) and she was messing with this guy trying to make him uncomfortable by getting all close to him and touching him. It was all fun at first and she told me it didn't mean anything, but then she started trying to kiss him. It got so far that she refused to leave the place we were at until this guy (he's really shy) did it. Eventually they made me look away (I was able to watch anyway) and they kissed. It was kinda quick but it was a definite kiss. Then later she was telling me this plan of hers to rub up against him (in a very sexual way) to make him even more uncomfortable and I was just like what the hell?! We played truth or dare with all of us later and they got dared to make out for a few seconds. That didn't bother me as much because I know it wasn't her decision, but at the same time I know she wanted too!

I know she had a flirty party kind of personality but it really pisses me off that she did that. I didn't say much at the time other than "hey you wanna stop kissing other guys?!" I didn't let her know how strongly I felt. But it made me feel like shit. Like I said it was a month ago, so I don't want to make her feel bad or start a fight by bringing it back up again, but it still gets to me! Should I say something or just try and let it go or what? How do I 'get over it'?

Oh, and for the record she's not a slut. I'm the second she's ever had sex with and she's had opportunities from flirty guys/players before.

Can you succinctly summarize the text in 1-3 sentences?
<bot>: Girlfriend flirted with and kissed another dude in front of me. I know she likes him too. It happened a month ago but still is bothering me! What do I do?