Nope. There may certainly be psychological reasons people stay with other people who routinely beat the shit out of them, but that doesn't make it any less stupid or wrong. Said people need to get their act together, figure out what's causing them to be a willing punching bag, and get the hell out. Coddling them or treating them as completely blameless for their situation does nothing but enable them to be a victim. Not to mention that I find it rather patronizing. "Oh, we mustn't judge the poor dear, she probably didn't know any better!"

If we expect him to be able to figure out that beating people up is wrong, despite whatever psychological issues he has that cause him to react that way, then we can expect her to figure out that letting herself get beaten up regularly is also wrong, despite her issues. They're both grownups and probably have similar mental capacities.