The summer heat seemed to have permanently settled in their home. The air conditioner, out of order for weeks, transformed the rooms into damp greenhouses, and Marina, 22, was at her wit's end trying to keep cool. Dressed in nothing but short shorts and a tank top that bared her sun-kissed shoulders, she sprawled out on the living room couch, hoping to catch a breeze from the open window.

This was her second week back at her mom's place after breaking up with Lucas. Two years of being together ...