sudden aggression

I have had my male and female Acaras for about a month now and everything was fine and dandy, they were swimming together, sharring the same hideouts and such and now all of a sudden my male is being a jerk. My female is only a bit smaller than he is and now she is forced to hide all the time and when she comes out my male chases her and trys to nip her. Should I try adding dither fishes? Get another female or two to even out the aggression? any suggestions are apreciated.

Thanks in advance