I'm glad you were able to find a wonderful home for Alex. I know how rough it is to deal with rabbits that really don't want to bond. After a certain amount of time, it can just become too stressful for them and it's no good for everyone.
I can't remember how Ryo and Alex came together in the first place? I know with my two girls that don't get along, I did not bunny date them first as I was taking in Bailey because she had some major health issues that needed attention.
It took me 8 months for them to get along, but Bailey would always end up picking fights and being extremely bossy with Rucy, and it just started causing health issues with Rucy. After a year, I thought I'd try again, and Rucy was happy to try and bond with Bailey, but Bailey was havin' non of it, and as soon as I would turn my back she would chomp right into Rucy. So I finally just gave up and I am lucky to have the room to keep them separated.
Some bunnies are solo bunnies, while others are just picky about their mates. I don't know which one they were, but it sounds like it's better for everyone, and you made sure that Alex had loving owners. So many people just turn their rabbits into animal care and control where they would be at risk for euthanasia, so I give you big kudos for making sure your bunny was safe and loved!
Though it must be hard because you loved Alex, it must make you feel settled to know he's a great home, and you can get updates.