If a person loves another and I mean truly Loves a person, they learn to respect the boundaries of another. Even if what excites them to their core may never be done. It is because one at the end of the day must choose between a personal satisfaction or the person.
Trust me I cry, I feel loss, and it hurts, but I make the active choice to be with the human soul of another …
This is unconditional love.
As for your observation, it maybe due to the fact you are afraid (and rightfully so) that violence maybe returned. But do understand, you are right violence has no place in bed.
Now if a guy like him is into pain, the use of implements to separate the physicality maybe important. The thing is though what does he give back for the act where you as a person have to shutdown your emotion and love to create the act. It does have in impact on your being, mind, and soul.
So if this was a long term partner, talks would have to be done outside of the bedroom, without alcohol/drugs, and has to be talked about a lot before the act happens …. How it appears to have been done with you and him is not about a lifestyle decision (IMO) but a raw emotion without thought and that means there is no consent ….. just lust and anger absent of love.
That is not a good mix, and you were wise for saying no.