WordNet sense 1 (unhappy in love; suffering from unrequited love):

lovelorn, unbeloved

WordNet sense 2 (not loved):

unloved

WordNet sense 3 (sorrowful through loss or deprivation):

bereaved, mourning, grief-stricken, grieving, sorrowing

WordNet sense 4 (experiencing or marked by or expressing sorrow especially that associated with irreparable loss):

sorrowful