the paradox of love

Spinoza renounces romantic love, writing that (quoted by Rebecca Goldstein in Betraying Spinoza):

Emotional distress and unhappiness have their origin especially in excessive love towards a thing subject to considerable instability, a thing which we can never possess. For nobody is disturbed or anxious about anything unless he loves it, nor do wrongs, suspicions, enmities, etc. arise except form love toward things which nobody can truly posses.

And Amoz Oz writes in his memoir A Tale of Love and Darkness:

Love is a curious mixture of opposites, a blend of extreme selfishness and total devotion. A paradox! Besides which, love, everybody is always talking about love, love, but love isn't something you choose, you catch it, like a disease, you get trapped in it, like a disaster.

Yet even the most rational of people crave this temporary insanity that takes an almost unbearable emotional toll on its victims (except maybe Spinoza, but it was speculated that that might have been because a girl broke his heart early on and he never really recovered). Seems almost counterintuitive.