We have two dwarf Holland lops, one male, one female. They are about two months apart in age. We originally got Dmitri and Sasha together, but lost Sasha after two months. We got Tipsy because I read that rabbits need to bond with another rabbit no matter how much their humans love them. They've been together now for about seven months. They bonded immediately. Dmitri was protective of her when she first arrived, because she was so tiny, but Tipsy has proved to be quite spirited, and bold. Dmitri is almost a year old, and Tipsy is about two months behind. They have never seemed to have a problem until last night. They started chasing each other in a circle, and tried to nip at each other. It looks like Dmitri is the aggressor in this. We separated them for the night. My daughter is watching them today. She tried putting them together and they were okay for a bit, but then started again. Dmitri is happy as a clam now that they are apart, and Tipsy seems upset and withdrawn. What should we be doing about this?