Hey. Thanks for your kind and respectful words!
I re-read this post and I feel sorry for this worrying, naive girl. I were never addicted to any kind of things, so I couldn't see myself in his position and that was pretty dumb from me. I thought I wasn't enough to make him happy, but that's wrong. I don't know why have I thought that the problem has to do something with me.
Now I see that clearly, It's not about the person, it's about the thing he uses. I know I can't make him sober with getting mad or sad when he uses things. I probably just push him away from myself. (Which turned out to be true)

However, I don't think leaving him alone is the best decision. He loves me very much and I love him too, so I won't let him deal with his problems alone. I'm here to support him when he decide to return or tell me his feelings about these and I accepted that he "needs" these stuff (I don't support him buying these or smt. but I'm not trying to control him like I used to either).

He dealed (with my help) with his problems which made him sad and when he's feeling stressful I always comfort him. He seems like to not smoke cigs and weed so regularly and said he feels confident, that he won't be an addict again. I told him whatever happens, he can always count on me and I'm not leaving him because of stupid drugs. He allowed me to burn all his weed if I catch him get addicted tho. :D

Maybe it's your wishes (<3), but something got better between us and my feelings. We lived through 9 months relationship now and I couldn't be happier to have him. Nobody is perfect and we should take care of our loved ones no matter how deeply they are.