Lovesick

[Vania]

A deep, often depressing, feeling of wanting to find love; to be [loning] for love; to be without a companion to share ones life with, though it is desired deeply.
(Dont believe the other definition that has all those thumbs up for saying it is [being in love] and drawing hearts in the sand and stuff, becauase that is the opposite, that is [lovestruck], not lovesick).

[Sommer]

In love, or missing the person one loves, so much that one is unable to act normally.

[Zipporah Schumaker]

sad because the person you love does not love you: