Indeed, he did, here is the whole quote: “For one human being to love another; that is perhaps the most difficult of all our tasks, the ultimate, the last test and proof, the work for which all other work is but preparation. I hold this to be the highest task for a bond between two people: that each protects the solitude of the other.
This is the miracle that happens every time to those who really love: the more they give, the more they possess.”

― Rainer Maria Rilke, Letters to a Young Poet