Would be creepy in real life but sounds cute in manga form. The age gap has to be more than just a mere 2-3 years differences, where the female lead is a full-blown adult and has a stable career while the guy is less established, maybe still in his highschool or college. Hentai is ok as long as it has good and sensible plot. Preferably something lighthearted. No harem tho. Thank you XD

Edit: wait... I do know an example, Present wa Shinju lol

DONDAKEE!!

My hit or miss recommendations. All of these are shounen or seinen though.
This is something you might like.
Hitorimi Haduki-san to.

If you don't mind borderline H then this is good. Although I don't remember how big the age gap is.
Toshiue no Hito

I also don't remember the age gap on this one but I still recommend it.
Bonnouji

Avoid:
Kono Onee-san wa Fiction Desu!? The ending sucks.

first I just had "Zoku Sensei no Okiniiri!" but I dont thing this really fits and it is smut :-/ not really even a good one for my opinion.
Maybe Kimi wa Pet is the right thing for you 🙂

Most of this guy's manga have that kind of setting
https://www.mangaupdates.com/authors.html?id=1554

Maybe Story of Someone We Know ?

Game Over
14-sai no Koi