I honestly don’t remember much about the main story ..... what I do know is the main character falls in love with his best friend and it’s in a school setting. That’s basically it for the main story that I remember (this is why I’m trying to find it)

However I do remember the “bonus”/side chapter.
So the main character has a little brother who fell in love with his childhood friend of course it’s mutual and they do ecchi stuff together etc etc. Then after high school they decide to move in with each other and they’re finally alone so they can finally “do it” but the childhood friend either changes the topic, says he busy, or etc. So the little brother character begins to think it’s because he doesn’t love him any more and basically burst into tears in front of his partner. Then the childhood friend character finally says the reason they stopped doing ecchi stuff because as he matured his pe*ns got darker and he was afraid that his partner would think it’s gross. They make up, they “do it”, and the end.

I used to love this manga because the art was really good and it’s been about 6 to 7 years since I read it so it’s not new, and I’ve been racking my head about this for the last few weeks please help!