Your BF needs to be hit with a healthy load of balance, he's getting too extreme now.

You can still go out to the same restaurants that you used to, and if he needs larger portions then he can either eat more before/after your meal, or just tell him to pack a protein bar for dessert to make up the difference.

Same with the alcohol really. It's fine if he just doesn't want to drink, but if he does want to and is denying himself for this physical image then he needs to chill.

Every bodybuilder has cheat meals, and many drink socially (though not when prepping for shows). He needs to find balance, and that's probably going to be the best way to get through to him. I'm sure he gives his muscles rest days to recover, he needs to give his overall lifestyle the same courtesy.