While this manga has a lot of the same pitfalls and tropes of other BL, which I don't see any need to get into, I do want to address the age gap.

The characters start as a teacher and student in a different class and after the time skip are both adults working alongside each other. The uke is very concerned about their age gap and I feel like it was handled better than most other age gaps. They address his insecurities over being visibly older, and being worried that his younger lover will start looking for someone closer in age. While the art doesn't reflect a much older man very well (the art style has somewhat bishounen faces for every guy) the sentiment is felt enough. That being said, there's probably way too many misunderstandings and suspecting infidelity in my opinion. It's a pretty constant theme for them to not handle seeing each other with other people well, or being jealous when they spend time with others and becoming possessive or insecure. It's not enough to make me stop reading, but it is a bit annoying when after it happens and gets resolved, then suddenly it happens again. Otherwise I'm enjoying it and am looking forward to them finally feeling comfortable with each other to the point of a story resolution.