The poem consists of a series of questions, each beginning with the phrase "How do I love thee?" followed by a description of the speaker's love. The repetition of this phrase creates a sense of monotony and predictability, suggesting that the speaker's love is straightforward and uncomplicated.
However, as the poem progresses, the speaker's descriptions of their love become increasingly elaborate and passionate. They compare their love to the depths of the ocean, the height of the sky, and the strength of the wind. The contrast between the simple structure of the poem and the intensity of the speaker's emotions creates a sense of irony, as if the speaker is trying to express something that is beyond words.
This irony is further emphasized by the fact that the speaker never actually provides an answer to the question "How do I love thee?" Instead, they simply offer a series of metaphors and similes, suggesting that their love is so complex and multifaceted that it cannot be fully expressed in words.
Overall, the irony in the poem "How Do I Love Thee?" arises from the tension between the poem's simple structure and the speaker's passionate and intense emotions, creating a sense of understatement and suggesting that the speaker's love is beyond the limits of language.