That's honestly one of my biggest problems with a lot of not only bara manga, but hentai in general and even some anime(like Gravitation). I just don't like the whole "you like this, you're such a pervert" while the character getting used appears to genuinely be hating the humiliation. This seems pretty prominent in bara manga from Japan, so I can't say I like a lot of the storylines. If someone enjoys being "abused" they are still going to show genuine enjoyment, even if it's only a hint of it.
That being said, Trap is my least favorite of Tagame's works. The man character is nothing but an absolute p***y.