I've been reading The Art of Cruelty by Maggie Nelson and there's tons of great extracts and references. One that caught me in particular was this excerpt from The Ivy Crown by William Carlos Williams, which (I think) disputes the rosy typical notions about love but reaffirms it as a wilder, more brutal thing:

The business of love is cruelty which, by our wills, we transform to live together.

It's a nice disputation of the oft-quoted 1 Corinthians 13:4-7:

Love is patient, love is kind... blah blah