He killed himself because he finally wanted to be happy.  However, in the end, he was still unhappy.  He walks days and days in those same clothes.  White v-neck and a pair of dark blue jeans.  His hair is almost as bright as the sun but just a tad duller.  This man can't be seen but he can walk through anything.  He sees them crying with saddened tears.  If his heart was still beating right now, it would break into a million pieces.  Kris Wu asks himself, "What have I done?"