Whether a male is abusive to females is not actually dependent on how many females he has; if he's inclined to be abusive then you can give him more females than he can ever mate with and he will still pick some to repeatedly abuse. If he's not inclined to be abusive you can put him in a population where he has to share females or perhaps even only ever gets to look at them, never mate, and he's not going to be abusive.
Some males are inclined to be clumsy when over-excited, i.e. when they've been apart from females for a while, which isn't the same as deliberate abuse, and most young males are clumsy due to inexperience, but good males just won't be abusive no matter what whereas bad ones need no reason and that's just 'their style' and you can't do anything much to change it. Unfortunately too many people think it's normal for males to abuse females and turn a blind eye to the damage and distress their females have to live under, and tell others it's normal too. It's not natural, and not healthy, though it may be common enough to call 'normal'... But good males are also normal so it's 'choose-your-normal' if you get what I mean. I don't breed female-abusive males, it's a strongly heritable trait and the females' quality of life is equally important to me if not more so as they produce eggs etc whereas a male's value is limited to what offspring he may sire, which value is nullified if he's abusive and harms the females or chicks or passes on that mentality which is quite likely.
A wild male who brutalizes his mate/s is far less likely to pass on his genes than one who doesn't, and I don't believe in being the 'safety net' that allows a domestic male with such a vicious mentality to pass on his nasty attitudes. I also won't help chick-killing females to pass on their traits, I don't believe in helping animals pass on their genetics when their mentalities are so violent that they would naturally eradicate themselves from the genepool.
Ducks are pretty prone to some aggressive sexualized behaviors, but he's not a wild duck and as far as I've read, some wild drakes are opportunistic abusers to unpaired females, but paired drakes are not abusive to their partners.
It's not even a reproductive tactic to be abusive and force matings, since females have to be willing and cooperative in order to allow successful mating as they have numerous 'dead ends' with which to prevent drakes achieving conception via forced matings... But then again some drakes will force mating on anything they can, no matter the gender, age, or species. Some animals are like that, it's got nothing to do with reproduction and does not represent a normal relationship nor mating for the species and is not the norm for all males of that species either. It's an aberration. Domestic animals in particular are notorious for aberrant instincts in all areas thanks to human intervention, but some are also present in the wild, the famous case of the wild mallard drake repeatedly mating with another adult wild mallard drake, a dead one, comes to mind.
He's paired, so chances are he won't be violent to her. Hopefully they will continue to get along.
Best wishes.
