Personally I see 2 things: ignore and carry on, in fact ignore sounds too active of a verb, more like simply carry on with your night on the other hand you could literally walk over and take her away from them in a "My house, my rules" way.

Nobody wants to be the lingerer who's joining conversation. Ive seen it work to some EXTREME cases but as Kowalski said; have some respect.

My friend once spent like an hour of an already short night just hanging around 2 girls arguing hoping to get a make-out at the end. He did but really? A whole hour of being some therapist to some girls with less-than-winning personalities.

Respect for the fact he got the make-out immediately after they stopped bitching and crying.