Why should I blame her that she filled my days With misery, (lines 1-2)
The first thing on the speaker's mind is how Gonne contributed to his own sufferings. He does not mention the instability in Ireland until the next lines. Does this mean that he blames her first and foremost for the failure of their relationship, and that everything else is an afterthought? On the other hand, he never follows up on his "misery" in the rest of the poem.
or that she would of late Have taught to ignorant men most violent ways, (lines 2-3)
Uh-oh. A contemporary reader might view these lines as the most serious allegation against Gonne. We tend to value people who find nonviolent means to protest against oppression, like Gandhi or Martin Luther King, Jr. Still, the verb "taught" is ambiguous, and it is hard to know exactly what Yeats means.
Or hurled the little streets upon the great, (line 4)
Boy, this image sure makes Gonne seem like one powerful lady. She's picking up one street and throwing it on top of another! Maybe the speaker overestimates just how much influence she has, simply because she had so much influence over <em>him</em>. But that's just one possible interpretation. The little streets represent the oppressed working class, while the great streets represent those in power, like the British colonists.
Why, what could she have done being what she is? (line 11)
This line seems to give Gonne a break and to suggest that maybe she is not responsible for inciting violence after all. But look closer: he gives her a break because she could not help being who she is...that's like saying to someone in an argument, "Well, I guess you just couldn't help it, because you're such a jerk!"
Was there another Troy for her to burn? (line 12)
The speaker puts Gonne's actions in a historical and metaphorical context, comparing her irresponsibility to the irresponsibility of those whose actions caused the destruction of a great city. That's a pretty heavy burden to lay at her feet.