Love's stricken "why" — Hesitating Love

Love's stricken "why" 1
Is all that love can speak-
Built of but just a syllable
The hugest hearts that break.
(F.1392/J.1368)
[1] why:: a hesitating reply without commitment, and a question.
[2] love:: one's lover.
[3] syllable:: a meaningless sound.
[4] break:: it's the reluctance that breaks one's heart.