A study conducted at Concordia University (Montreal) proved that love intensifies after sexual intercourse. Sexual attraction and the feeling of love are controlled by the same areas of the brain, so a simple lust for the flesh can very likely develop into a deeper feeling. It is precisely because of the lack of intimacy that unrequited love quickly fades, while platonic love, reinforced by good sex, is reignited.
Scientists have previously established that love has the same roots as drug addiction and gluttony: falling in love affects a person in the same way as certain narcotic substances, and orgasm activates the same areas of the brain as the anticipation of a delicious meal.