It's kinda weird. The only reason other characters treat MC like a gloomy person is because the author says he is. In reality he's more an unsecure guy that a gloomy type. He is able to hold a normal conversation and smiles pretty often. As a result other characters acting like he was unfriendly just turns out feeling mean spirited. A shame because If the characters weren't forced to act this way by bad writing the MC would make friends pretty easily.