It is interesting how we might not fully appreciate the relationships our companion animals have with each other until something different happens.
Monty and Mitzi share a cage and have never been apart until Mitzi's overnight stay at the vets. Monty is very docile but Mitzi henpecks him. She will bully him off perches if she wants to be there, she will chase him and pull his tail. They never groom each other but they do kiss.
In the evening when Mitzi was away Monty was walking around on the floor of the cage and looking up as if he was looking for her. When I uncovered the cage the next morning he was quiet and he was much quieter than normal all day. He wouldn't sit on his favourite perch, he didn't eat much, he didn't play with his toys and he looked very sad, just sitting hunched up all day, with his head drooped down.
When I got Mitzi home in the evening the first thing she did when I put her in the cage was go and give Monty a kiss.
Somewhere in another universe, dear brother, you got saved.
I remember how Manzi and Maui used to fight. And I was worried that one was stressing out the other. But the first time I bought a big outdoor cage and transferred one first, the other one was calling nonstop and I realized that even though they'd bicker, they still had some kind of comforting relationship with each other.