There is hardly any activity, any enterprise, which is started with such tremendous hopes and expectations, and yet, which fails so regularly, as love.
— Erich Fromm, The Art of Loving
Fromm was a psychologist, psychoanalyst, sociologist, and philosopher. His book The Art of Loving, is small, occasionally repetitive, and hard to read; and yet despite all this: quite brilliant. Maria Popova and her Brain Pickings blog has a great review.