I know some think MC changed love interest pretty quickly but I don't. He knows his feelings for that awful Junwoo aren't reciprocated and realized before anyone else that Junwoo is developing feelings for Taesan. MC is never going to have what he wants with Junwoo so it's best to keep silent about it all and not lose him as a friend. Jun has only now realized he could be attract to Yohan so things are progressing nicely.
Keep calm and read Yaoi^-^