It happens sometimes. An aggressive female can turn against it mate (for no rhyme or reason) and bully it to the point where fins tear, the male stops eating or the female kills the male. Not much you can do other than isolate the female, rearrange the rock work, wait a couple of days and reintroduce at night. Definitely observe closely. If the bullying continues, cut your loses and rehome the male.
You can always try and introduce another male down the road (or a couple with the hopes that the bullying is evenly distributed and one makes it). But there is no guarantee.
When this happen to me to a pair that was together for 4 years, she ended up killing the male. I rehomed her and just bought another pair.