I think you would like this one, but it's a pretty old manga from the 70s, so it might be different from what you usually read, (it's a tragedy).
https://www.mangago.me/read-manga/heart_of_thomas/
So, it's not exactly one-sided but also kind of ? And if you want to shed tears, I think you should try it. It sure made me cry.
https://www.mangago.me/read-manga/10_years_where_i_loved_you_the_most/

I need a bl or shounen ai with unrequited love, heavily one sided. And no I don't want a happy ending and they get to be the one they wanted to be with. If you know any please recommend it to me
I'm ready to shed a tear of two, thanks in advance