“The sincerity of love that is willing to sacrifice is the essence of noble love. Love that does not think of itself. Love that is willing to do anything for the happiness of the person it loves.”
Related quotes

Source: Dictionary of Burning Words of Brilliant Writers (1895), P. 272.
“Who wills, Can.
Who tries, Does.
Who loves, Lives.”
Source: "Dragonrider", published in Analog (January 1968), p. 148; also in Dragonsong, (1976) Ch. 7, p. 89

“Being in Love means being willing to ruin yourself for the other person.”
Source: As Consciousness is Harnessed to Flesh: Journals and Notebooks, 1964-1980

“I'm not willing just to be tolerated. That wounds my love of love and of liberty.”
Source: The White Book
Speech at Massachusetts Institute of Technology, Cambridge (September 26, 1975). "The Root Cause", ch. 9, Our Blood (1976).