@rtanto,
rtanto, you are a faithful soul and expect the same from your partner.
Jealous is a waste of space let's face it and I'm glad you've gone through life in trusting relationships and had successful ones.
My thoughts are:-
1. Perhaps he has an identity problem with himself, does not feel that he is good looking enough and therefore eyes off others intensely
2. Perhaps he has not been faithful in his past relationships and isn't ready for a commitment.
3. Perhaps this time you may have got it wrong, see above, he may not be ready for a committed relationship.
In the event he does cheat on you, it's not a reflection of yourself, as you've stated your sexual relation is good, love is there.
You are correct, you can't change him and what will be, will be. I would though given your track record ask him, in the event he ever decided to cheat and was caught in that moment, freeze, halt, walk a way, leave you and then do what he wants..
I'm not sure how you can solve this, love is love, "in-love" is totally different you are thick and thin in every aspect and wouldn't even contemplate it.
Perhaps sit down and view your relationship without the rose coloured glasses and see if anything is missing in that relationship that you both can build on.