You will understand.
"To My Wife" is organized as a kind of ballad with three feet per line (except for the last line of the second quatrain which has but two). The first stanza serves as an introduction that seems to state that a proper introduction is not possible.
At first glance, the second stanza expresses a romantic sentiment. However, the poet's poems or "fallen petals" are described as only having the potential to reach his wife's hair. Note, they do not have the power to penetrate her skull to reach her brain and thereby be appreciated. It is only when, in the third stanza, that hard times befall his wife, that she will be able to understand the true meaning of her husband's poetry.