Pearl Jam - the full quote. From "Black" - sung by Eddie Vedder.
“Love is a temporary madness, it erupts like volcanoes and then subsides. And when it subsides, you have to make a decision. You have to work out whether your roots have so entwined together that it is inconceivable that you should ever part. Because this is what love is. Love itself is what is left over when being in love has burned away, and this is both an art and a fortunate accident.”