I don’t think it’s the subs. Unless he is tapering off. When you reduce your dose, something happens. Maybe you gain sensation again. Maybe it’s related to nerves and receptors. Idk. But most people report having a marked increase in desire to have sex, and also an increase in sensation. That increase in sensation leads to really fast/ premature ejaculation. Like when most guys come completely off of suboxone, or any opiate for that matter, after a few days off they jack off a lot. Like ten times a day. Also, the increased sensitivity makes you ejaculate really really really fast. Talking seconds to minutes. Basically he becomes a 13 year old all over again. Random boners and two second sessions.
Anyways, I’m not sure if that’s the case with him. On suboxone, unless he’s rapidly tapering, and drastically cutting his dose, then suboxone shouldn’t be causing this issues. Actually, if anything, and he’s taking it in his normal dose, or especially a higher dose, it would cause the opposite effect most likely. At least to some extent. It takes forever to achieve climax on higher doses of suboxone, or at doses higher than you’re used to. A lot of guys report having sex for hours at that point. To the point where it’s frustrating. Also, being less sensitized at higher doses diminishes the climax it’s self.
So it would probably depend on his situation with the subs right now. Could be a number of things. Including that he’s not taking them, with plans to relapse, and not telling you. But that’s something you would have a lot more of a guess than most of us, considering no one here knows him, or his situation, and mental space at the moment. If you can’t directly relate it to suboxone at glance, I would hit a doctor. Could be a number of underlying medical issues, including low testosterone which suboxone can impact, could just be stress or other mental states causing the issue, or any number of other factors. That can be an extremely frustrating thing though, so it’s probably worth looking into. It often doesn’t go away on its own and can drive a real wedge into a relationship,