My partner adopted a cat before we got together; a male, neutered, huge tabby. He was around two when he got him and he's six now. We got three kittens (2 female, 1 male, same litter) mid 2020.
He's always been a grumpy boy before me or the kittens moved in. He likes his own space and likes attention on his terms. We had some territory trouble with him when we got the kittens as it was his domain and they were moving in but then we moved house in December last year and it seemed to fix everything as it wasn't just his territory anymore and he seemed to just accept that like magic. Honestly he was much less grumpy and tolerable of the kittens (not really kittens anymore but I'll call them that to differentiate), even playing with them and letting one of them rub up against him.
I've noticed sometimes he'll pin the girls and bite their necks which I've recently learnt is a sexual thing. That's always as far as it goes, the girls usually whine and he leaves them be after and that's it.
He's been particularly grumpy this past couple of weeks though, and has seemed aggravated easily by the kittens (he grumbles and scampers off to an area of the house they're not in, he never fights them) and has been grumpy with me too.
We just had a knock on the door from our neighbour two doors down and she asked if the big tabby was ours and she said he keeps attacking her female cat and she's had to take her to the vets twice because of him - one of the times he's bitten and punctured her cat's arm. I honestly just don't know what to do. We can't keep him inside because all four of them are outdoor cats and we've tried keeping them in and they hate it and do everything they can to get out.
I feel awful about her cat and she's not sure if it's a sexual thing or not with them both being neutered. Has anyone experienced anything like this before? I just don't know what to do to stop him attacking the other cat.
I've ordered some more felliway to see if that would help calm him down but I don't know if it'll be enough.