Dating LTR for 8 months. Found trp 1 month ago. I'm 24 6'2" 130lbs... dead skinny. Recently laid off, I played WoW like 12 hours a day for the last year but dropped it, I'm maybe a 5-6. Basically I'm a beta and my gf is a bit of an unstable bitch.

Everyone involved in this are 21-26. She just moved into a new apartment with a girl roommate. They have neighbors upstairs - two guy roommates, same age as us. They've apparently been drinking for the past few weekends together, just chilling and playing video games, as told by my gf, her roommate and my other friend who was with them (trust his word on it)

Well after 2 weeks of my gf drinking with these guys, I show up on the 3rd weekend. It felt like I killed the vibe when I showed up - they were already hanging out. Then we started drinking.

We're all pretty drunk now, having fun, me and the guys are getting along, they seem like bros. The night goes on, all is well. Then my gf tells a story about how she fucked some guy a while back who was famous-ish. The one guy (their neighbor) starts having a convo with my gf where there's a lot of flirting, IOIs etc. going on, hes teasing her about being a slut, about fucking anyone with "over 50 followers". I try to cut in and joi n the convo and my gf holds her finger up to me as I talk, because the guy is talking. Straight up disrespectful. So I walk out of the room, obviously upset but not pissed, just like "lol okay whatever"

Then I go out for a smoke. A few mins goes by and the guy, the neighbor, comes outside. He lights a joint and passes it to me. I refuse, he keeps smoking it, after a few puffs he offers it again and I take it.

Him: Look, I wanted to talk to you man to man.
Me: Ok. About what?
Him: Your girl. She's into me.
Me: I don't think so man... We've been dating for 8 months, she's a bit nuts sometimes but she's not a whore.
Him: Bro, this is gonna come off as an insult, but I'm telling you right now, if I fuck your girlfriend I'll let you know.

and he walked away. I stood there for a while, pissed as fuck and really drunk. Eventually I didnt have a key to get in so I went around back and knocked on the window. Of coure THE GUY opens the blinds and everyone's looking at the window, and he laughs and then my gf comes and lets me in.

This was last night I haven't talked to my gf. Just woke up a few hours ago and have been contemplating what to do.

So wtf. Do I just dump her? Is he bullshitting? There's obv some tension between them. What the fuck man. I know you're probably thinking the guy is jacked and super good looking but that's what baffles me - hes like the same as me, maybe a bit better looking face, but tall and lanky like me, unemployed like me, gamer like me....