Being sober became lonely he realized drinking was the way he bonded with his friends. Without it they had no way to relate or connect. He realized they'd bad mouth others he'd wonder if he did the same when they were with other people.
He use to like listening to others problems maybe he can learn and grow. But he got tired of providing advice or saying what he would do just to be ignored. He helped them by being a friend while they talked bad but he never shared or told their secrets.
He didn't like when they'd cheat or expect him to cover by saying they were with him. He didn't like to cover or lie when it was none of his business in the first place.