A marriage which begins with passionate love and leads to children who are desired and loved ought to produce so deep a tie between a man and woman that they will feel something infinitely precious in their companionship, even after sexual passion has decayed, and even if either or both feels sexual passion for someone else. This mellowing of marriage has been prevented by jealousy, but jealousy, though it is an instinctive emotion, is one which can be controlled if it is recognized as bad, and not supposed to be the expression of a just moral indignation
Source: Bertrand Russell :Marriage and Morals, 1929
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