«Canst thou, O cruel! say I love thee not,
When I against myself with thee partake?».
Sonnet 149 recalls the poet’s abject defense of the youth’s insulting behavior. The main theme, however, is the conflict between reason and infatuation.
Canst thou, O cruel! say I love thee not,
Bemoaning the woman’s treatment of him even more fervently than before, the poet is quickly slipping into madness: “Canst thou, O cruel, say I love thee not / When I against myself with thee partake?” Such questioning continues throughout the sonnet, with each question designed to convince the woman of all that the poet sacrifices for her benefit. The poet has even gone so far as to forego all friendships with other people.
He asks her, “Who hateth thee that I do call my friend? / On whom frown’st thou that I do fawn upon?” Having alienated himself from his friends, the poet now finds himself in the ironic position of having alienated himself from the woman because of his blinding love for her. His calling the woman “love” in the concluding couplet balances his first calling her “O cruel” in line 1: “But, love, hate on, for now I know thy mind; / Those that can see thou lov’st, and I am blind.” The woman, then, rejects the poet for the very reason that he is losing his mind — his unreasoning passion for her.
English audio from YouTube Channel Socratica
Summary from Cliffsnotes.com