Caution is the word.
Im a woman's lib guy and if I see a man & woman tussling Im gonna handle it the same way as if I saw 2 guys fighting. I will try to calm things down & make sure neither one gets hurt - but if things escalate I will just as likely back off as not.
Years ago in a bar parking lot I pulled a guy off a gal he was beating the slobber out of. He wanted to fight so I got him down and was handling him when his "victim" hit me in the back with a brick. When the LEO showed up she accused me of being the aggressor & showed him the swollen eye I gave her.
When sharing this story Ive heard of similar experiences from others.
One couple saw a big black guy accosting a small woman. He was on top of her in the parking lot. Hubby jumped in & the wife was going for her pepper spray when they learned the "thug" was store security and the gal was a crack head shop lifter trying to flee and screaming rape.
Recently a couple moved down the street. The guy is unfriendly and will not acknowledge anyone who waves at him. The LEO's come to his house 3-4 times a month & the records published in the local paper shows arrests for DV & PI- as a result, the neighborhood has been talking about what a louse he is. We learned later that the gal drinks all day and then attacks the guy when he comes home from work!
These people arent worth more than a 911 call from me.