I have similar probs with my 2nd but not abt stealing my youth lol
I feel you. The last guy I dated, I was pretty sure he mentioned that he was 32 BEFORE we dated. We were coworkers. And then when we were dating, I asked him again, just to confirm for myself, he suddenly said he's 27. I was 23/24. It confused me, especially since he has a 1986 tattoo on his arm. I asked him about it and he said "oh, that's the year my aunt was born." I think he knew I wasn't buying it because he started acting really immature and distant after that, like he was afraid that I'd dump him for being older. But eventually, I dumped him because he kept cancelling our dates on the day of and started saying some very misogynistic things to me.
In my last year of high school, I dated a man older than me and the age gap can be a real issue. He kept worrying about "stealing my youth" because we didn't go out to parties or whatever, he broke it off even though I was serious. Too much of an age gap really does look like what's shown in this manga. (No, he was not my teacher.)