Hello and welcome!
Bonding two males is a bit trickier but there are lots of cases of success and most times it does work out, so no worries on that note!
Just to get a bit more info, what specifically have you tried? Have you done any face to face dates with them yet? If so, what was the bonding area like (size, set up, how neutral)?
From the set-up you described, I think they would benefit from a slightly different housing situation (although they will not be super happy about it at first). Right now they are dif rooms, so they have both set up their own territories. I recommend setting them up in side-by-side pens in the same room, with a buffer of about 6 inches or so between them so they can’t nip each other through the fence. Make sure the pens are tall enough that they can’t jump over (you’d be amazed at how high buns will jump when they really want to “get at” another bun). For exercise, you can either divide the room in half with a pen (again with either a buffer, or some small mesh attached so they can’t nip noses though the fence), or alternate who gets exercise (like one bun gets morning and one gets evening). Then, swap which bun is in which pen every day or two. I try to time it so the litter boxes are a bit dirty (so I clean boxes one day, and then swap sides the next day). The idea here is that they start to lose track of their territory and get very used to the other bunnies scent. It also helps to feed them on opposite sides of the fence so they start to associate the other bun with good things and realize the world is not going to end just because another bunny is around. This kind of set up is kind of a pain for the humans and means the buns will have slightly less space and exercise, but it’s temporary!
You want to do these swaps until both buns seem very relaxed about the whole thing, and are not behaving aggressively towards each other through the fence (usually this takes 1-3 weeks). You may see behavior mirroring and laying near each other, which is a good side. Once they are calm etc you can start face to face dating in neutral territory, but continue the side swaps during actual dates too.
I’ll stop there for now, but curious to hear what you have tried so far with them!
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The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.