Compromise this

Last night, I was talking to one of my best friends on messenger. He's telling me about how one of his boyfriend's friends came over last night and says "We all smoked." I'm thinking, "Wait...what?" but let him continue and he says something else about how his boyfriend just wanted to get stoned. So I have to say something then, and I ask him if they were smoking cigarettes or weed. He tells me weed. I flip out, mentally, but I try to stay come as I talk to him about this. Basically, I tell him I don't like that he's smoking weed, I don't like that his boyfriend is the one pressuring him to do it, I don't like that his boyfriend is making him feel like he has to smoke weed so boyfriend will be happy. And I basically tell him to stop. He tells me he doesn't even like smoking weird, but he just not do it otherwise boyfriend will get butt hurt. So we make a deal that he may smoke weed once every two weeks (and cut back to once a month) and any other time that boyfriend decides to smoke, he'll leave and go work out or do something that gets him out of there.

Now, I'm not saying I'm perfect. But I have never done drugs. I learned not to do that crap because I watched my oldest sister screw up her life by doing drugs. My friend knows this. He knows how I had reacted when I found out said sister was still doing drugs (before she died after being a victim of a hit and run). And he even admitted that he does like smoking pot because it just makes him hyper (which is normal for him...) but then he crashes so that his brain associates weed with the crashing part. But he still does it. And that's what I don't understand. How can someone who claims to love you allow you to harm yourself in some way in order to make them happy? For me, this whole situation shows that boyfriend only cares about himself. He doesn't care about my friend like he claims to. He only cares about what will make him, boyfriend, happy. And I hate him for that. My friend even told me that boyfriend doesn't understand loyalty to friends, but he can't see that boyfriend only cares for himself. And that hurts me. My friends doesn't seem to realize that I care about him a lot. And I want him to be happy. But I don't think he is happy now. I think he's just doing whatever he can to make boyfriend happy. Which means that boyfriend is so far on my bad side now that it would take a miracle for him to get back on my good side.

While I've never had a relationship or love (or even a boyfriend), I know the kind of guy I do want. And I know that if any guy tries to get me to compromise my principles to make him happy, he's gone. For me, a relationship has to make both people happy. Not be about making one person happy so much so that the other person will harm themselves and compromise their happiness for the other. People say love is blind. And I just don't understand it. I don't understand how people will stay in relationships that aren't good for them. And I wish I knew a way to make my friend see that he needs to get out of this relationship.