How does the cadence or music of the poem affect the tone?

When they laid you in the crook
of my arms like a bouquet and I looked
into your eyes, dark bits of evening sky,
I thought, of course this is you,
like a person who has never seen the sea
can recognize it instantly.

They pulled you from me like a cork
and all the love flowed out. I adored you
with the squandering passion of spring
that shoots green from every pore.

You dug me out like a well. You lit
the deadwood of my heart. You pinned me
to the earth with the points of stars.

I was sure that kind of love would be
enough. I thought I was your mother.
How could I have known that over and over
you would crack the sky like lightning,
illuminating all my fears, my weaknesses, my sins.

Massive the burden this flesh
must learn to bear, like mules of love.