I have two Maine Coons, a male and a female, unrelated but both almost four years old. I've had them since they were twelve weeks, they're both neutered, and they're indoor cats.
Sadly, even though they've been together since they were young, they don't cuddle up together or groom each other. At best, they tolerate each other - occasionally they'll both sleep on our bed, but never touching. They're individually very affectionate with me so it's a bit of a timeshare arrangement for my lap. Once every now and again they'll play together, but inevitably it quickly gets rough and the boy is much bigger than the girl so she ends up screeching as if she's being murdered (she's not, she's just a drama queen).
I have Feliway plugins, they have separate beds, litter trays, food and water bowls, and they seem happy enough. But I'd love them to love each other! It would be nice if they cuddled up when I'm away, so it's not just the cat sitter that gives them affection.
Is it too late? Can I do anything to make them closer and happier?