Follows iambic pentameter throughout- 5 sets of unstressed stressed syllable pairs.
However, stresses fall on the first, third and fifth syllables of the first line, rather than the second, fourth and sixth, as would be expected.
Irregular stress pattern gives the sense of a tripping motion, perhaps mirroring the way the speaker has fallen for the woman.
The comma in middle of first line further disrupts the expected pentameter by creating a pause. This metrical confusion represents the confusion in the speaker's heart and mind.