<human>: Can you succinctly summarize the text in 1-3 sentences?

He's had this planned for a while. He and his friends got really into DMT recently, and chose today to do it for the first time. He's talked to me about it A LOT, and has known from the beginning that I disapprove and that it upsets me. 

I don't know why it upsets me. Possible reasons include that I don't like the guy who's influencing him to do this, that my brother is a recovering drug addict, that my best friend had a psychotic break down after too much psychedelic use, that most of the people I know who use psychedelics regularly are extremely dumb and hard to respect, or that he seems to have taken a position of vague superiority for knowing so much about DMT and being so open minded about it -- and feels that it's "ok" for him to do it because he's educated himself on the subject. None of these feels quite right though. 

Otherwise, I'm quite open-minded about drugs. We've done shrooms together, and he smokes pot occasionally and it only rustles me jimmies occasionally. I want to not be upset about him doing this, but I can't help it, and it makes it worse that he doesn't seem to take my feelings about it into account. 

I am worried that this situation will alter the dynamic of our relationship negatively and I'm not sure I'll have the wherewithal to stick around. I'm putting concerted effort into trying to be open minded, to not give a fuck, to know that this is his life and he should be free to live it regardless of our relationship status, but it's still bothering the fuck out of me. Any help?
<bot>: Boyfriend is doing DMT today, it upsets me but I don't know why, he knows but seems to dismiss it, worried the resulting feelings surrounding it will ruing our relationship.