I missed some posts when I was typing but others are giving the other side to what I said.
If he can control it around others, then it is abuse.
He is choosing not to control it around you.
There is also something else to consider.
The dynamic of yours ad his relationship is exactly that. The dynamic of yours and his relationship.
Not the dynamic of his relationship with anyone else, but with you.
It may well be that he has enough of a handle on his feelings through therapy to be able to create different dynamics with other people but the dynamic with you was established a long time ago. It's a pattern of behaviour, it's a habit, it's essentially the story of the relationship between you both.
Does that make sense?
It's very hard to change a long established dynamic of a relationship.
Think of a friendship. You have a friend with whom you always discuss politics and serious issues. You enjoy the friendship. You enjoy the debates. You enjoy the intellectual challenges. That is the dynamic of your friendship. How easy do you think it would be to change this dynamic to a light hearted funfilled one where you talk bollocks and ESewawwwlaugh at nothing?
You both have other friends with whom you have fun and belly laugh but, with this friend, you automatically fall into the dynamic of serious conversations.
It's very hard to change the dynamics of a long standing relationship because you each have an understood and accepted role into which you fall. It feels out of place, uncomfortable and just a bit strange to try and change it.
So, even if he were able to relax differently to other people, the dynamic between you and him will remain the same. You will fall into your role and he will fall into his.