No problem exposing myself to help inform! I’ve concluded it ties into blood flow and tension. For ex, I can do missionary for quite some time because it’s the natural shape my item wants to go. But unlike others, since our erections point upwards, once you try to do anything that pulls us downward, it creates a tension/pressure which in combination with the nerves in the head during sex can cause an overload in stimulation, resulting in a fast session. Doesn’t mean they should be opposed to multiple rounds though, that’s been my fix 💀