Cats at war

[humblesims]

About ten years ago I took on two rescue cats. At the time I thought they would be company for each other. They were rescued from the same place at the same time.
It was evident quite quickly that they didnt really care for each other much but as they had different life styles (ones a little female who stays close to home and mostly indoors and the other a large dominant male who is a wide ranging outdoor cat) their paths only really crossed when the male came in for meals or in the evening when he came in for a sleep.
As the years have gone by their relationship has become quite accrimonious and for some reason the male, a couple of years ago, started a habit of intimidating the little cat in an attempt to get me to feed him (I cant quite unravel the psychology because its never resulted in me feeding him) and upsetting her.
This has gone on how for a couple of years and we (and she) have tolerated it as its quite random and it doesnt get physical.
This summer the big male cat had to have eye drops for a short while and really hated it and as a result he spent most of the summer out of the house and not even returning for food. I would see him in the garden every day and could see that he was healthy and I assume he has been stealing food from somewhere (as I say he has a huge territory) and sleeping in the outhouses. Either that or he has been being fed by someone else (he's a very attractive and friendly cat). I have tried to find out where he's been going (asked about on facebook and attached a paper collar to him) but no idea where he's been getting fed.
Anyway ...during the whole summer while he's been 'away' the little girl cat has been very much happier and more relaxed. She is now an elderly lady and in the autumn of her life so I think she has enjoyed not having the big cat around.
But...(sorry this is so long!) now the weather has changed and the big cat is back. I think whereever he's been getting food as either sussed him out or started shutting their doors?
He is back to his old trick of winding little girl cat up and making her hiss and screech in an attempt to get me to feed him.
Now she is so elderly its upsetting for her (and sets me on edge).
I'm not sure what to do.
I'm sure I could have shortened all that story!
Any ideas. I dont want to rehome him, he's a lovely cat apart from this bad habit.