hey, I think this manga is more shounen ai.
but anyway, the first scene of the manga is boy1 confessing to boy2. if I'm not wrong boy1 confessed at a busstop and the friends of boy1 and 2 are present during the confession. boy2 accept his confession. at the beginning boy1 was very cute and shorter than boy2. but boy1 started to grow taller and his voice started to change. this made boy1 scared because he thinks that boy2 agreed to go out with him only because he is cute. boy1 decided to not speak around boy2 cause his voice had changed. in the end they broke up but met again when boy1 entered boy2 high school.

thank you so much
sorry for my bad english.

Pretty sure this is it. I had to hunt around in my files, but I knew I'd seen it. It's a oneshot.

Kaze ni Chiru Hanabira to Kisu

Your English is fine.

Thank you Thank you so much