I think it's a really complex issue, this. As mentioned, men are expected to be strong, to be able to take physical punishment, etc. It's also pretty embarrassing for a lot of guys to admit that their girlfriends/wives control them in any way at all, let alone through physical abuse (or, perhaps more shamefully, sexual abuse). I've known many guys who have suffered through horrendous abuse by women, but have been to embarrassed or too emotionally attached to do anything, or who just took it because that's what men are supposed to do. Take it, and not hit back. I know some who were then accused by their abusers of being abusers - the women telling the police they only hit him because he started it. Thankfully, in those cases, the women's stories were inconsistent enough for the charges to be dropped.
One of the big complicating factors comes down to, if you ask me, the basic size difference there is between a lot of guys and their girlfriends/wives. Men tend to be bigger. When a big person hits a small person, there's more chance of damage than when a small person hits a big person. Because of that simple fact, I think a lot of abusive behaviour perpetrated by women goes unnoticed because guys don't have to (or are to stubborn to, or too embarrassed to) go to a hospital or a doctor afterwards in the same numbers that women might. Or, maddeningly, it's considered funny. "Look at that little girl hitting that big guy!" It happens in clubs all the time. Rarely, a bouncer will do something about it - but always a female bouncer, in my experience.
It's not exactly a husband-wife dynamic, but it's illustrative of my point: I remember going to an all-male strip club and a drunk woman ran up on-stage and fondled one of the dancers. The dancer looked terrified, put his hands in the air, and tried to walk away from her while she chased after him, trying to get another grab at his crotch; she didn't even come up to his shoulders - and she had heels on - and was probably less than half his weight. If he'd hit her (and I can't say I would have blamed him), she probably would have been knocked right off the stage, and I would bet the police would have had to get involved. Instead, it ended because the dancer ran off and the woman went back to gab with her friends.
He didn't touch her. People laughed, and the bouncers did nothing.
