Okej, let's see if I can describe it good enough to find out what the name of the manga is.

The only things that I remember is:

1. The pair meet in HS. The seme is I think one year younger than the uke.
2. The uke has a friend that is actually in love with him, but because the uke is straight he isn't sure of what to do and when the seme comes in the picture, the friend is first just letting him be to see if the uke could perhapse switch sides.
3. Just a small detail, but one of the strongest that I remembered (for some reason). The uke likes to sleep with the blanket covering his face when he sleeps, even in the summer. And the first time we get to hear about it is when he is sleeping in a sickbed at school (don't remember why).

There are some more details that I remember, but they are so fragmented that it's hard to describe them.
But I hope that it maybe is jugging someones memory of which manga it could be.

This? https://www.mangaupdates.com/series/ypytwxb/hatsukoi-counter-attack

No, not that one.
But a good recomendation. 🙂🙂