Someone like this has not developed past toddler stage in terms of regulating their emotions and expecting everything to be done to pander to their feelings and insecurities, while they in contrast are free to do what they like. There is no equality and no notion of it.
There is also a total lack of empathy.
At the root of this is stunted development and self regulation, if that hasn't happened by a certain age - probably a good bit younger than he is - its extremely unlikely to happen.
He's failed to develop emotionally as a healthy, functional adult.
You are suffering as a result. He's making you suffer.
I'm sorry but I doubt there will be any fixing him. An ex of mine suffered from this "affliction" and he has been like that from first getting into relationships, until his (so far) 50s ..from what I can see.
There was no changing him.
The certainly in his head that I was doing him wrong by socialising separately (because he couldn't deal.with his feelings about it) and his feeling of absolute justification & righteousness in resenting, criticising, berating and punishing me for it - was so deep rooted in his character and values, that it wasn't going to change.
When someone on here wrote about emotional development and maturity, a penny dropped and I started to put it all together with his interactions with other people, his attitudes, his background ...everything. He'd never grown up emotionally. He'd never got to the point that decently adjusted people do as they grow through childhood, adolescence, young adulthood etc.
I wound also wonder just what is behind his insecurity and lack of trust and certainty that you would be up to something with other men; with zero background, it's very odd how untrusting, paranoid, suspicious etc he is. One has to wonder whether it's projection.