My NZ buck hates to be alone. He's ALWAYS had a cagemate...first his brother (who was delicious), and then a tiny little Mini Rex doe. He let her totally dominate him, which was hilarious...here's this hulking ten-pound white monster, and a little ball of fluff that'd fit the palm of your hand, totally bossing him around. She would use him as a shelf...more than once I caught her standing on him to reach the top of the cage-high floor-to-ceiling hay rack. When I fed them, she'd eat first and drive him away if he tried to eat too, so funny! She got out and alas, found the only poisonous thing in the basement (ironically left there by the landlord, dangit) and he got really depressed. It was the final push to my decision (for many reasons) to set up a colony room, so he could have a doe or three as constant companions. He's always super-submissive to every other rabbit, and seems to LOVE having kits around...I swear if he could nurse them he'd be a better mom than the doe who birthed 'em!
Right now I'm rethinking the colony setup though...because my two sibling-does, who were never separated except when going to a show.............have decided that they'd like to just kill each other and be done with it.
So...long story short (too late?), Bison (the NZ buck) does in fact like living with at least one other rabbit...he does get lonely and he does seem depressed when alone. He readily bonds instantly to the nearest living being, and submits at all times to does no matter how tiny.
Bubbly, the Champagne doe he's with right now, seems to barely tolerate his existence. Her sister Sparkles is currently living in my "grow out" pen because, as said, she and her sister have decided to make war, not love.
I think it all boils down to several factors...had I separated Bison and his brother, would Bison be more comfortable alone? I am unsure. Could Bubbly and Sparkles be "bonded" and be happier together as friends? HECK NO, it might work temporarily but long-term? No, someone would decide sooner or later, "I'm gonna kill her NOW."
Here's my issue: to me, it is not worth the risk. I am totally down with colony settings but given the social temperament of the Champagne does, I doubt it will work for me any longer. That's ok...I've learned a lot from my colony setting.
But know this: one rabbit wounding or killing another will be very unlikely in my herd, since aside from Bison and one-Champagne-doe-at-a-time, nobody will live with anybody ever again except for growing kits in the grow-out pens.
If I was selling something, and someone said "I need two or they'll die of loneliness" I'd warn them of all the hazards of housing rabbits together. The cure is likely gonna be worse than the "problem!!!"