The great American poet James Merrill, whose father founded the brokerage company Merrill Lynch, James Merrill wrote an amazing poem about why we marry.

We marry because in summer the green of orchards grows around us and creates leaves, and fruit, and promise, the way tree trunks each year grow bark around the old trunk to make the trees we see.

But then winter gives us second thoughts. After all, leaves fall off of trees.

But when the spring comes again, the world brightens, and it occurs to us that love is like a tree. Trees grow many trunks, one for each year, wrapped inside one another like matrushkas, Russian dolls.

And who are we to act any differently than trees? Year after year we add new worlds to old, to finally make the orchards that we come to love.

James Merrill puts it much better.