I read this manga a long time ago, so my description may be somewhat lacking. However, I am going to try my best. I am also sure it is on my 'complete list' but no matter how many times I search for it I overlook it somehow. Anyway, this is what I remember...

So, the first (main) story is about a school teacher who comes to visit his students parents for some reason. Instead of the parents, the student is being cared for by his older brother. I believe the older brother has light hair. But anyway, the teacher and the older brother get into a relationship. The second story is about the student and his friend. In one scene that I remember the student's legs are held by the older brother while his friend is screwing him. There is also another brother (I believe he is the middle brother) who is always shut up in his room for some reason or another. I don't remember if there is a story about him or not...

This is all I remember. Hopefully someone will know what manga I am talking about ^.^ Thanks in advance.

maybe Aruhi Totsuzen Koi wa Kuru?!

Yup, that is it! Thanks so much ^.^ ~