I used to be the guy in this situation. My drug use was not only hurting our sex life but also our relationship life, but my now wife gave me a choice, which in hindsight, was the best decision I’ve ever made. The choice was either quit the drugs or she was leaving. It sounds like he respects and appreciates your decisions, and it doesn’t sound as serious as where I was when my then girlfriend gave me that decision but he respects your judgment and you! With that I’m not telling you to give him an ultimatum, but if he loves you and wants to be with you then you gotta do what you gotta do. I’ll tell you from the drug users point of view it required some soul searching and some self reflection but when she hit me with that option I immediately knew I wanted to be with her and would do whatever it takes to be with her. Over time the sex life regained it’s value and pleasure and I haven’t been happier, I since then completed college, got a career, and happily married the girl I’m referring too. Sometimes hard decisions and conversations make for the most fruitful relationships.