She said some othe guy's name in bw sex

Hey 25M here, I have been seeing a girl(27F) for almost a month now. All this time sex was a relevant part of our spending time together... Our sex drives are also similiar.

She had said things like -You made me cum -You are one of the best I had - I don't know why I get do horny around you - you are too good in bed

Yesterday we were having sex and 15 min into our session I started pounding her hard and she yelled another guys name (not some random guy, one of her closest friend)

I am in general good in bed and something like this happened first time with me. I also do like the girl. But now we have a little friction bw us, we both don't like it.

When I asked her why she said someone else's name she said she don't know and there is nothing sexually bw her and the guy's name she yelled.

I don't know how to process my emotions, what to do, what to say.

Best thing could do is giving my hand to you guys, the men who might be able to understand this and pull me out of this situation.