As stated in the title, I'm looking for a manga, manhwa or webtoon. I don't remember which it was exactly, sorry. The plot goes something like this;

A girl befriends two boys and finds out that they are/were in a relationship (WINK WINK). It'sall rather very cute. One of them is obsessed with phone stickers or something, and keeps plastering them on the phones of people he likes. Also, it might have been a webtoon. that's very possible.

PLEASE I NEED HELP, ANY AND ALL IS APPRECIATED

Should be That Summer (KIM Hyun).

Shit, thanks fam