I'm going to say my boyfriend should drink less
Why do you want him to drink less?
I want him to live longer.
It's good to look out for loved ones. You should discuss the negative effects of drinking with your boyfriend. He might be more receptive if you approach the topic as a conversation.
We're in a fight if he doesn't listen to me. He'll want to drink afterwards.
It's not your responsibility if he chooses to drink afterwards. all you can do is voice your concerns and see what he thinks about it. You can't control whether he drinks or not.