Bro reddit is extremely biased towards women. Lets be real, if this was the other way around and you and your homies were getting the hot neighbor girl to come over, these people would be pulling out their pitchforks. You are in a bad situation with having to spend time with only women.

Imo, you should go talk to that guy on your own and try to become bros with him, see what kind've person he is. But in the end if your girl does cheat it does save you some time as she would've cheated at some point anyways.

But try not to look insecure though, that will make her lose attraction/respect for you. You got to not seem worried, even though their actions are a bit worrying. It's pretty much a giant shit test to see how stoic you are.

Tread carefully, keep your dignity, stay stoic