This reminded me of a manga I've read before (Boku no Kirai na Otouto story of Stockholm syndrome) the younger brother is very possessive of his older brother to the point of confining him in a room. However, this is kinda different since the relationship is kouhai / senpai but the behavior is similar. In the end, they still ended up being together.
Kawaii Senpai no Kaigoroshikata