I don't know why it bothers me so much To be bluntly honest, the only person that's coming off creepy, based on whats been written, is you. Let the man enjoy his young trim as long as it lasts. As far as I know, she never said anything, but it was evident that the situation was stressing her out. But whatever your reasons, I don't think you are wrong or selfish or unreasonable for having the feelings you are having. Even if the parents feel like they can't tell their adult daughter who she can and cannot date, it blows my mind that they're allowing her middle aged boyfriend to crash with them. Admittedly, that email strikes me as tone deaf, but evidence that she is at least trying.
Daughters refuse to meet dad’s girlfriend who is the same age as them
You really don't have to approve to accept.
Ask Michael Cohen: Why Age Matters When Dating
This is one of the best questions I have ever received. The student-teacher thing usually doesn't fare well and if she were to date you, she is either a gold digger I'm assuming as a teacher you aren't a millionaire or she has daddy issues, none of which are attractive. I'd give my left breast for that atTITude.