Yeaaah, that's a hard nope from me to the ML. I'm okay with the classic "domineering ML" we see in a lot of these stories, but domineering =/= scumbag rapist. I even managed to get myself sorta comfortable with a 10,000-year-old ML who fell in love with the 14-year-old who saved him ONLY after it was established that he was willing to wait until she was older before starting a relationship with her; was domineering to everyone EXCEPT her and would obey literally any commands she had, supporting her from behind every so often but also backing off whenever she said she could handle something herself; and it was established that due to the way cultivation levels extended lifespans and youthfulness meaning people could physically appear younger than they were, age-gaps between lovers was not super rare. Even after he found out the FL was reincarnated and was "technically" an adult, he didn't push her until she said she was ready and pretty much courted her rather than just "whisking her away to ravish her into submission" since he knew she was rather 'flat' when it came to emotions and had no understanding of romantic love in either lives. It also didn't cross into "grooming" territory, as he would show up from time to time and come when she called, but she had an actual family (which grew constantly because every adorable old man she met would adopt her as their surrogate granddaughter, which was super wholesome as two of them argued over which of their granddaughters were better before they realized they were both talking about her), so he didn't take on any actual parental/authority figure role. If I remember right, he actually waited like until she was 17/18 and she had figured out she liked him romantically before they made any real progress, and even that was only after she went on the attack.
But yeah, Mr. "Sneak into your room and molest you after paralyzing you" is waaaaay too far. The only way they can even approach redeeming this ML is if the "eunuch" part of his title happens after the FL get her hands on him.