dwarf ram

they're not "rams", they're Apistogramma and yes, aggression of the male toward the female is common.

http://www.apistogramma.com/

Yes, best thing you can do for her is add not one, but three or four more caves scattered around the tank. Feed a variety of frozen foods and do weekly 50% water changes. With luck the female will spawn and then it will be the male that is forced to hide in caves.

Worst case senario, you might have to remove the male for a few weeks to condition the female and let her rest up. It looks like he would do fine in either of your other tanks.

I was under the impression that a. cacatuoides are harem spawners. In that case, it may help to add 1-2 more females, if you have the room. In either case, you need to add more caves, and this species really likes planted tanks as well.