One friend is immature, the other is mature.
Stop coddling this guy. Be who you are. If he doesn't applaud your talent, he isn't much of a friend.
I don't really think either is mature, they are simply immature in different ways.
If the OP were really mature, he'd tell his friend that he wasn't enjoying playing with him because he feels like he is having to, as Ms. Crimi states, coddle him.
I play pool to win. I am not going to practice banks, play only centerball, play difficult shots or do any other condescending things to my opponent. I will beat them. I will be nice to them and if there is a problem they want to discuss, I will listen.
As a last thought, if your friend is much of a friend, he should recognize your improvement and be happy for you.