I have no idea, just trying to guess by read hair blue hair i hope it is this one
The plot sounds similar to Cherry Blossoms After Winter but idk if this the one you're looking for. The main characters are not red and blue haired tho
Maybe you mean this?
https://www.mangago.me/read-manga/hush_today/
https://www.mangago.me/read-manga/my_last_love_scenario/ (sequel)
Haha yes this one!! Tysm!!!
It had a red and blue haired character and they’re childhood friends (now that I think about it, i feel like they had different hair colors BUT the plot remains the same!). The other has a crush and obviously, the other one doesn’t know. They were both either in high school or middle school but I remembered there’s a 19+ sequel because the first season was PG rated lol anyway, this was like maybe 5+ years ago manhwa?? It’s been so long but I forgot what the name was ;;; can someone please help me?
Edit: the sequel was them graduated already in college and they live together.