I think it would be OK for them to see one another. Chickens are flock animals and seem to do best when in the company of other chickens. Is there some way to divide their current space with chicken wire or something so they each have some room? I wouldn't feel right leaving a chicken in a cage...
A mature rooster has to earn the right to breed with a hen. A good rooster will call his hens over and show them food that he's found, dance for them, and be the leader of the flock. I think your guy is too young for that yet.
I would definitely separate them for a time. Right now you have the equivalent of a teenage boy in with a middle aged woman. She's treating him as the bird on the bottom of the pecking order, which he is. Give him a chance to grow up a bit. May I ask if you have this pair for mating reasons? If...