I would say that some things to note are:
1. FL is currently in the guise of a man. There is literally nothing wrong with looking or having skinship with a man in this story's setting. As seen in the first chapters of the story, Aenon himself is also very disapproving of a man touching, even loosening the corset of someone who is suffocating. Overall it doesn't make sense for you to "look at this from the perspective of a lady" since Aenon is not treating the FL as a lady in the first place, and it is quite unfair to judge his character from his actions alone without looking into the context of the story. I'm sure that Aenon would refrain from such actions if he saw the FL as a woman in the story.
2. This is Aenon's first time experiencing, or even in the process of realizing he likes the FL, and he is bound to make some "mistakes". And what's wrong with being a little possessive and jealous? Are men supposed to just suppress and hide their feelings? Why don't you comment on how the FL ogles the ML's abs, is that not creepy behaviour to you? Aenon has feelings too, and he needs time to learn, understand and control his slightly impulsive and barely intrusive behaviour. And it is not like he forces the FL to like him or does such things in a creepy forceful way that makes the FL uncomfortable, or not stopping when the FL asks him to.
I honestly don't know what makes Aenon creepy to you, since I've seen way worst out there in fiction and in real life. Aenon is one of the most respectful MLs out there, and if your justification for not liking him is because he is creepy, maybe your standards for men are too high.
Looking at this from the perspective of a lady who's supposed to be masquerading as a guy, isn't Aenon actually acting like a creep? Being possessive, observing Yuri everywhere, telling off other people while doing the same to Yuri, touching Yuri without permission just cause he's jealous. It's been so long since ch.1 and the only character I don't like is Aenon. He's a creep with a handsome face, there O said it. I'd literally rather ship Yuri with the Queen, or Ivy than him, maybe Lester but that's also kinda creepy for me.