How did you come up with that conclusion? The black haired guy never, not even once said that he loved or even liked the other guy despite knowing his feelings. Instead he just nearly forced himself on him without explaining anything which lead the other guy to believe he is just doing that out of sympathy. Do you expect him to just know the other guy has started to like him without the guy in question explaining it? Besides, the black haired guy didn't even realise that he is in love until the other guy left. So there was no "dropping anyone like a hot potato". One guy got tired of his one-sided love that he endured for a decade and he did so hoping to stay close to his loved one then he felt that he can no longer stay by his side since his feelings are known and he feels like he is burdening him.
Nooooooo I need to know what happens!! Leaving your friend of 10 years without even a word, how cruel. Like him having feelings for you is what you were hoping for right? Now that he shows them ya drop him like a hot potato.