Mystics can be pretty funky people. Pretty hard to understand. And pretty darn insightful.
Bernard de Clairvaux was a Christian mystic living in 12th century France. He was writing of the marriage possible between God and the soul, but the principal involved is universally applicable. He wrote:
...yet if the creature love with her whole self, nothing is wanting there where the whole is given. Wherefore as I have said, thus to love is to be joined together in wedlock, for it is impossible that a soul should love thus and not be beloved... (italics added)
Like the 'there is no returned love' principle, this one is guaranteed too. If you love with your whole soul, you can not but be beloved. It is impossible. If you love, you will be loved. There is no unreturned love.
Want love? Give love. Want a lot of love? Give a lot of love. Want ecstatic, overwhelming, heart-exploding love? Give all the love you've got inside you.