So let me get this straight Mr. Oliver Twist...I mean Wright
You have been practicing for 3 months, gotten a few lays ....and are shockingly stifled by a drunk guy. Well, not much you can do to "stop" him unless she wants to fuck him. Why do guys think they can actually stop drunken bafoonery from getting fucked? Too often, especially in nightgame, I am this drunk bafoon without the alcohol, and I have had many guys try to AMOG me...going like "hey dude dont touch my dick!" "Hey! wow u fucking creep. how many women did u touch tonight"
"didnt u just makeout with another girl?!?! Hey!! stop"
Realize it doesn't matter. You aren't actually even "practicing seduction" as much as you are practicing what I call something which requires relatively little seduction as you had mutual friends (and all it needed was the slightest inkling of directness on your side): Social circle game with a hint of directness.
You met a girl who isn't committed, in a very social situation in the comfort of a night club (where they are conditioned that it is okay to be slutty in some instances) and you got her number and closed her (kudos on this but don't kid yourself that she actually didn't game you). At least you know the mutual friends made it easy.
As for them being good friends, more than likely she has already fucked this guy multiple times, snorted cocaine off of his dick, or what have you. You haven't "lost the girl" because you actually do NOT HAVE the girl...so not sure what your problem is?
Competition to eliminate? What are you exactly trying to do? Get her to fuck you and only you? I'd say learn rule # 1 of seduction - moving on. If she wants to fuck the drunk guy, she will.
There's no magical routine, AMOGing tactic, etc you can do to stop that guy if he truly does not give a fuck for you. I hardly acknowledge dudes. Hardly. Anything they say, or even do is futile. I've fucked girls that have known guys and even fucked them before I come into the picture and they are left holding their dicks in their hands. It's inevitable.
As for what happens IF this happens to me, I just amp it up myself....and pretty much lock lips...but then at this point: you both are fucked (not literally).
Welcome to the game player.