山悦木兮木有枝心悦君兮君不知
[shān yuè mù xī mù yŏu zhī xīn yuè jūn xī jūn bù zhī]
This username comes from a classical poem, where it refers to the feeling of unrequited love or affection. 'Mountains delight in trees; I love you, but you do not know it.' It conveys the sentiment of hidden and unreturned affection.