From her beginnings as the goddess of the night, Luna was always seen as the incarnation of all things evil and responsible for the actions of all dark creatures influenced by said darkness… Which leads her to be feared and even hated by the followers of the light, composed by the majority of Equestria.
 
She’s never usually had a problem dealing with that; she cares very little what others think of her… But there are days in which the pressure caused by all the negative thoughts towards her and everything she’s made of adds up towards putting her in a small state of depression. Fortunately, the goddess of the night only needs a caring hug to get better.