Years ago I bonded two male's with no problems, I think they just matched well because even before they were neutered they got on. Added a female a few months later and again everything was fine, she didn't affect the boys bond at all. I currently have two boys living together, they're brothers and unfortunately had to be separated the day before they were neutered because of a big fight, but with the help of a lady from Small Paws Boarding they're friends again and have been fine since. It really just depends on the rabbits, I've had unneutered males get on brilliantly, spayed females who absoltely hate each other, and male/female pairs who would not get on either, some of my rabbits were really calm and easy to bond with one rabbit but horribly aggressive with another. Just stick with it, and as scary as it seems don't intervene unless they're really going to hurt each other. I made the mistake of separating mine as soon as they started chasing