It will blind you with tears
like a lover.
It will make your reflection
a wobbling photo of grief.
I am trying to be truthful.
Not a cute card or a kissogram.
I give you an onion.
Its fierce kiss will stay on your lips,
possessive and faithful
as we are,
for as long as we are.
Take it.
Its platinum loops shrink to a wedding-ring,
if you like.
Lethal.
Its scent will cling to your fingers,
Continuing the extended metaphor, Duffy compares an onion’s white ringed layers to a platinum wedding ring. 
 
 Note Duffy selects ‘platinum’ rather than gold, the former being the most expensive metal, symbolising the high value she places on the relationship. 
 The word ‘shrink’ is perhaps a jarring note, suggesting that love might diminish or might be confined and restricted, that marriage can damage it. This may fit the message of the poem, which is concerned with complexity and reality in relationships. It could be that ‘shrinks’ is exactly what Duffy intended.
Valentine