What is an example of metaphor in the novel, Alternate Side?

Nina uses her desk as a metaphor/symbol about marriage. When looking at the desk, she sometimes "remembered how thrilling it had been to spot it across a dusty plain at an antiques show, even though nowadays she mainly cursed its sticky drawers and splintery edges" (144). She believes this is how most marriages operate, the spouses mostly take each other for granted or focus on flaws, but sometimes something happens to remind them of the joy they felt when they first encountered the other person and fell in love.