My boyfriend and I have been dating for 2.5 years and have a future ahead of us. I love him with all of me and would do anything to make him happy.
Last night we got into an argument regarding him smoking. He was not a smoker when we began dating, but during a short break early on in the relationship, he turned to it to cope. As we got back together, he felt he didn’t need weed anymore and “put it to the side”. Over the years, he has lied, and gone behind my back to smoke with friends. Recently, we agreed that I would be more open to the idea of smoking if he could maintain honesty and good communication about it, which I thought would help. He told me he was going to the clinic for a ‘pickup’ last night and it affected me more than I expected. I’ve always had a problem with his smoking (I have smoked before), just because I feel like a distance is created between us when he his high, and I have to treat him differently. He smokes leisurely, (once a week) because he sees absolutely no problem with it.
I can’t explain what I don’t like about smoking without saying I just don’t like it. In our argument, he said he would do anything for me out of love, except for quit smoking, because it’s something he enjoys and wants to do. I don’t want to give him an ultimatum because he’d be stopping for the wrong reason. Is it wrong for me to be upset with him? He wants me to respect his desires, but it makes my wishes feel unheard. He’s willing to agree to disagree. What do I do/say?
LemonVibe 
You don’t like it and he’s caused trust issues by going behind your back.
Depending on which state you live in it could be illegal and get him in trouble, which would put you in trouble monitarily. Who will be paying the rent, bail, etc.
He’s not going to stop for you. He did it behind your back and will just give you whatever you need to hear, so he can do it again. This is a mark of a addict.
You need to decide if this is a deal breaker for you. If it is, then please move on now, so you don’t waste any more time when you can be finding someone who has what you need out of a relationship. Better to hurt now, than hurt for years.
Youd “do anything to make him happy” but you cant accept his smoking, which he says he enjoys.
To be honest its his body and his choice and you cant force him to quit, I certainly wouldnt say that smoking once a week makes it an “addiction”. And if you cant accept his vices then this might just be the deal breaker for you. Weed is a touchy subject. I know everyone has their own opinions on it. Some see it as nothing more than an herbal remedy, others see it as a terrible illegal drug. And then theres every morally gray opinion in between. You two may never be on the same page on the topic and if he sees it at no big deal hes probably never going to see it as the huge problem you feel that it is.
But, try to talk to him, tell him how you feel about how hes different when hes high. It might not change anything but at least you will have made you feelings known.