Yanno, it's fine with me of this ML is Ace (by which, for clarity, I mean Asexual), or some other demi-something, and therefore just doesn't have any romantic interest in anybody, but he needs to stop leading the ladies on toward a relationship and be clear about his utter lack of interest.
If the ML is
NOT Ace, then he has had
plenty of time to decide that he is disgusted by these women, and
(fucking again!), needs to make his dislike clear to MC and the other FL.
(Demon Queen is plainly the main character; silly boys can get over it.)
And, if
none of these scenario are true...
So, the hero is aware of the demon queen's desire for intimacy with him, and can become a completely different person who will enjoy looking at other women, and he's basically sworn marriage vows... but he's still going to leave the demon queen hanging like a knob.
Why can't these stories stop degrading themselves with artificial drama and poor writing when it comes to romance? Maybe Miyazaki was right, about animators (and, I'll add, artists) not living life enough and spending far too much time in the anime culture. They don't know how to write realistic relationships anymore.
... then I would have to agree that the ML is basically a piece of shit towards women, either due to him intentionally being written as a fuckwaddish turdbag, or due to the Miyazaki Hypothesis™.
(As a corollary to the Miyazaki Hypothesis, it worries me that people who have no contact with the real world are writing stories to be read and digested by other people who have no/limited contact with the outside world, creating a nasty feedback loop that causes people to think this behavior is
normal, and therefore begin to mimic these wildly idiotic tropes; it has already happened in the US with the -chan groups online, with much more hateful tropes and actions, so it's not just some wild idea... I've lost friends to this bullshit.)
Ultimately, this writing is a bit concerning (not a lot, just a little) in its incompetent delivery of bullshit messaging... but the story is still fun enough for me to keep reading, I think.