The guy that got hot splashed is obviously not an aggressive, warrior, fighter type. First off, she knew it. That's why she did it, plus the social condition encourages it.

However, that said, the guy needed to compose himself before he struck them.

Easier said than done in the moment, but he should have feigned some sort of cheek turn, approached the guy in the spirit of forgiveness, and as soon as he could get close, square up and break his fucking nose.

Once he bloodied him up, all well and good, slowly approached the dumbass GF and grab her cell phone and smash it under his heel.

Then maker her run away.

If the dude with the bloody nose attempts another strike, then hammer him again, second blow would be a hard kick to the crotch.

Composure is the key in these moments.