The lines posted originally were from Sonnet 140: "That I may not be so, nor thou belied/Bear thine eyes straight, though thy proud heart go wide."
Earlier there is a an ironic paean to love's falsity in Sonnet 138 since it is in the willingness of lovers to accept the lies of their partners that the habit of trust often develops. Now, in Sonnet 140, the lover bemoans this "ill-wresting world" that has grown so false that "mad slanderers by mad ears believed be"; the worst liars are believed by those wishing to be deceived.
The lover does not want to have "mad ears" and be so deceived. Nor does he want his lover to prove so false; consequently, he asks his lover to keep her "eyes straight," being true with her loving looks, even if she strays some in her "proud heart."
In this sonnet Shakespeare emphatically states that he is devoted and loyal to his lover and explains in detail the many ways he wishes to serve her faithfully: "Do I not think on thee, when I forgot/Am of myself, all tyrant, for thy sake?" However, he is shocked and pained at her indifference and refusal to reciprocate his love and devotion: "Nay, if thou lour'st on me, do I not spend/Revenge upon myself with present moan?" He concludes by reasoning in the gemmel, that since love is always consisdered to be blind she is not able see and love what is right in front of her eyes: "But, love hate on, for now I know thy mind/Those that can see thou lov'st, and I am blind."
The real question of Sonnet 149 is who is this woman?
In fact, she is the lower soul of the poet, the part of all of us that accounts for the feelings of lust and anger. This insures that we will be fixated on lower biological urges, enabling us to reproduce and protect ourselves. We are compelled by nature -- God's plan -- to love this part of ourselves and serve it, as the poet tells us that he does.
This love blinds us to the "defect" of this way. We find this urge fascinating even though it may conflict with the desire for a higher, godly life, the aspect urged on us by our "higher soul," the latter represented as the "dear boy."
The "hate" felt from the lower part of himself is the contempt this part feels for the higher striving. Those that recognize this recognize that this is a form of love, but in the sonnet, the poet is in the phase where he is overwhelmed by these lower urges.
The two aspects are in opposition but are complementary and the good life consists of the balance we bring to the two urges.
In other words, this sonnet is part of the allegory that is Shakespeare's Sonnets. Its essence is identified in Sonnet 144 that describes these two "angels" that vie inside us. In this sonnet, the poet indulges in expressing his love for this lower part of himself.