I'm looking for a yaoi manga, cant remember the title but the uke is rejected by a classmate and sits on a bench to cry, when a little kid (seme) finds him and kisses him, promising to love him instead of the one who rejected. They dont actually do anything until the kid is older, but they date until then, it's a really cute manga

Puchi Puri by Mishima Kazuhiko.

Yes, that's the one! Thank you!