Ann Eliza Bleecker's "Written in the Retreat from Burgoyne"

Recently, I read Ann Eliza Bleecker's "Written in the Retreat from Burgoyne" in The Heath Anthology of American Literature (Volume One, Second Edition) and noticed some significance in the structure.  The majority of the poem is rhymed couplets (sometimes merely with slant rhymes), but these are interrupted at the point where Bleecker's daughter dies:

At length her languid eyes clos'd from the day,

The idol of my soul was torn away;

Her spirit fled and left me ghastly clay!

Obviously, instead of a pair of rhymed lines, there's a trio here.  This break from the established structure hints at the disruption that Bleecker's daughter's death has on her.  Later in the poem, she describes her profound grief.

Alternatively, this section could be seen as a pair (with the rhymes "day" and "away") followed by a single, unaccompanied line ("Her spirit fled and left me ghastly clay!").  In this reading, the lack of a poetic complement mirrors Bleecker's loss.