Hiii everyone, I'm sorry I won't be able to say much but I just randomly remembered the ending of this BL manga I read a while ago.
It involved some sort of supernatural/fantasy elements as the MC wanted to make the other guy forget all about him (I think by kissing?) but ofc it doesn't work, so while the MC is crying he just comes back saying he still loves him. Hoping I didn't make it up, thanks in advance!

maybe its Kamisama to Tobenai Tsukai

Mmh no, love that manga but it's not that one... I think it took place in a "normal" world. Thanks nonetheless!! <3

Does this plot sound familiar?

Gloomy protagonist meets a fairy guy who can change his size. Fairy eats happy emotions so he tries to make the protagonist happy.

He says he's going to make the protagonist forget everything, but the magic doesn't work and he remembers and waits for the fairy to return as he promised.

Not quite as you described, but the memory thing definitely sounds similar.

I forgot the title, read it a few weeks ago though so if it sounds right then I can search it out.

Hii you are talking about this one, right? Yousei-san wa Yaritai Houdai
Thanks but it's not this one either... I'm really starting to doubt whether there really were magical elements 🤣