could the first one be this?
https://www.mangago.me/read-manga/we_re_still_in_the_spring_of_life/
maybe this one? (I hope so bc I looked for a long time T_T)
https://www.mangago.me/read-manga/hishakaishindo/
no it's not that, thanks for trying to find out though, but how do I explain it....even i remember it very vaguely. I only remember the feeling it gave me. It was virgin x virgin though. They meet at the rooftop, and kind of like it's a hangout place for them. I guess they share a kiss on the rooftop as well.

1. so in this BL there was a guy(ML) who was really interested in rockets and was sort of autistic. the MC takes interest in him and they start talking as well. i guess they also go see a rocket launch together as well?
2. this one is vague as i really can't recall anything except that the MC and ML meet at the school rooftop. and the MC is like "I see this guy at rooftop alot, let's befriend him" or something like that. i know this is very vague, and there might be alot of BL mangas like this. but if you know this one please let me know.