They shouldn't be placed together until he is neutered and she is spayed. Rabbits are territorial and it's not natural for them to live together, as they may fight and hurt each other, plus they will get pregnant over and over, even twice at the same time which is terribly unhealthy for the doe. When breeding rabbits, you place her in his cage for 5-10 minutes and then you have to take her back out. If you didn't he could breed her again in a few days or even 2-3 weeks and she can carry two litters of rabbits born on different days or weeks. So it is useless to try to put them together. When they live together you have no control over when they will breed and then can't plan on when to put in the nest box or watch for health problems from the pregnancy. Keep him in a cage near her and that is enough for them. Rabbits don't pine away for each other. It's simply feeling the effects of their hormones wanting to breed. And once they mate, that's it for her. She should be by herself. If you want your rabbits to live together, get them fixed and then they won't be under the influence of their hormones and will also make better sweeter pets.