Q.E.D! or The Mathematical Proof of the Evanescence of Desire

You meet at the Lycée’s decathlon for science in Molyko; he is laughing at something  someone just said, and you are ready to leave. But the sun is blazing, and your brother is still roaming, so you duck into the canteen's shade to wait. When your eyes meet again, he is buying water from the woman beside you. You are not sure if he is smiling at you, or if it’s just the last drop of his previous laugh left hanging on his lips. But you need water too, so you walk up to the woman and say ‘hi’.