Wait what made you come to that conclusion (genuinely curious) Rush
I just reread it, it was ch3 page 26. Senpai reminisced him and seme together as basketball friends in the past. I think he had a crush on seme too but was not brave enough to stay by his side.
I just realized that senpai was also in love with the seme after a reread ⁄(⁄ ⁄·⁄ω⁄·⁄ ⁄)⁄ poor man, let him have a side story of something ╥﹏╥