Sometimes bondings are just not to be. I do not attempt a rebond more than twice. IMO it is not fare to force two Rabbits to cohabit if they just dont get along.
I am no expert and I *personally* dont agree with some of the harsh (IMO) bonding techniques so perhaps some people think I give up too soon. Well maybe, but rather too soon than too late...................
I'm thinking of getting Lucky another partner, and rehoming Jack because I can't cope with two single buns or two pairs
But you could be in the same situation again, if Lucky doesn't bond with a new bunny. Unless you can get a rescue to bond Lucky with one of their rabbits before bringing new rabbit home.
You could split the attic so that they could see each other, just not live together.
That's no more work than a pair up there
No advice, but I'm sorry to hear this has happened. I remember when you first came on talking about rehoming Jack and you've tried so hard to avoid having to do that.
Really hope you can find a solution that works for everyone.
Buns can be happy as single buns, I'm sure Jack would be much more happy in the attic split in two then getting moved out of where he knows and the people he knows to be a single bun in a rescue where he may stay for a long time if no one adopts him You've tried very hard with them, well done and if you could split the attic they could both see eachother so won't be alone.