I think the problem society has with female on male violence is firstly, we have this culture where women have to be loving, caring and nurturing and passive, so turning that view around to say women can be assertive, and then onto controlling and violent is difficult for people.
Then, when you look at abuse, the main point is that abusers generally pick on someone who won't fight back, this is how abuse, particularly in relationships, goes on and on for many years.
Women who don't fight back are often financially and emotionally dependent on their abuser. The practical problems of them moving out are quite large, they may become homeless, they many have no money, they often have children whom they cannot support financially. Perhaps their partner is very big and strong and they are physically intimidated.
Men who don't fight back are unlikely to be financially dependent on the abuser but they have some mechanism that is stopping them from standing up for themselves. Perhaps they hate confrontation (which is why the abuser picked on them in the first place), perhaps they feel "you shouldn't hit women" or stay through obligation, or embarrassment.
A man who doesn't leave is likely to be disbelieved because, in most cases, he financially could leave, he would still work, still have his salary, still have the means to live and eat. The man is alsophysically larger generally. Thus the disbelief is higher "what is stopping him leaving?" It is also felt, I think that a woman can't really physically hurt a man in the same way a man can hurt a woman. (A woman is unlikley to be able to strangle her partner). So men abused by women are seen as a small problem or a bit of a joke. A big bloke doesn't get a lot of sympathy from society for anything really.
The recognition of controlling and manipulative behaviour (emotional abuse)is still poorly recognised by a lot of people and the "cycle of abuse" is not a mainstream idea and so the mental pressure to remain with an abuser is discounted from the equation when "judging" the abused. Thus a woman who has 4 cracked ribs and a black eye is judged to have a reason to move, a woman or man who is undermined, controlled and abused emotionally is so difficult to spot that it is ignored.