Sungyeol is indredibly in love with his best friend, Myungsoo.  However, Myungsoo is afraid of relationships and Sungyeol respects that.  Myungsoo has stated that he will push away anyone who has feelings for him.  Sungyeol lives in fear of being pushed away by his best friend, but trying to gain Myungsoo's trust to hopefully show him that falling in love might not be such a bad thing.