<human>: Condense the text into a few key points

My [31 M] best friend [30 M] keeps bringing his girlfriend [26 F] with him into games.

I like playing games with my friend. He likes to play (the same) games with his girlfriend.

This results in often playing the game with the three of us. The thing is: I don't like his girlfriend. Thus, playing games (which I enjoy) with someone I don't like becomes very frustrating.

Simple solution would just to be to straight up say: "Hey I don't want to play this game with you". But what often happens is that me and my friend are starting to play a game, and then she asks to join in. In my opinion its socially unacceptable to say "No!" in that situation seeing that we are connected.

What's your opinion on this?

I sort of took action already by saying that I was going to avoid her a bit more (as in say I go do something else when she joins in or whatever.) But, sadly, I said it in a more war-declaring way.

But I feel like what I should've said is that: "It's not my girlfriend, I don't want to spend all my free time with her.
<bot>: Best friend girlfriend joins games. I don't want to spend all my free time with her, but its socially not that accepted to say otherwise.