They all expect "love" (which is nothing more than a chemical high in most cases) to last forever.
Real love, however is a choice. A choice to be true, kind, supportive, compassionate, and loving to the person you care for. To build something that isn't a high, but a state of conciousness and being, almost like a form of enlightenment.
Though these days i'd settle for a girl who was loyal and not an asshole, but good luck in this age where everyone is a selfish cunt regardless of sex or gender.