kinda a reach but.... hate mate?
mc had a supposedly unrequited love and it gets complicated as he struggles to move on. he ends up being with someone else later on. i enjoyed the closure between the characters. i heard the story was continued after the first finale but i haven't read that.
ALSOOO read monument! it's an anthology and there's a few stories in there that suit what you're looking for i think
https://www.mangago.me/read-manga/lucky_letter/
All about moving on, bereavement, spiraling and then recovering
https://www.mangago.me/read-manga/dear_gene/
Pretty emotionally mature, I can't remember if they get back together in the end or if they find themselves complete even without reconnection.
About moving on and finding closure? That at the end of the story, MC finally went on with his life after being entangled with ML; about forgiving, finding inner peace and going forward with life. There might be a potential new love interest for the MC but I prefer if he stayed single until the end and his "next love" is up for interpretation.