Please Help Me Find This Manga

So I'll try to explain what it's about but I can't remember much, I know that uke and seme went abroad like years later and got married, but little brother( I think) from seme (it's like last two chapters about that little brother) he has relationship with this other guy idk if it's just sexual or not and he calls his older brother to ask for advice for something, that's all I can remember if anyone knows please help I'm searching for it for so long~

While I was zoning out I remembered something. I saw this manhwa panel on pinterest, it was in a classroom and there are some guys in the back and a girl in front of them drawing something. She was actually drawing the 2 guys in the back being lovey-dovey (being a fujoshi lol). I srsly wanna know where it is from. Btw I remember the girl being blonde. Thank you!

It was a yoai manga about boy who don’t know any thing about his body ( he was thinking that he was sick ) but he meet other student who start to teach him and help him how jerk off