Aristophanes answer is seen by many as a comedic reply(despite him saying repeatedly it is not) which is seen as befitting his character considering he is a comedic playwritter. According to Aristophanes human beings were originally two parts of a whole being, four arms, four legs, two heads and two sets of genitals. They one day challenged the gods, in doing so they angered Zeus and as punishment, he cut human beings in half to cripple them and remind them not to go against the gods. The two halves were empty feeling the incipient need to try and attach to their missing half to feel whole once more. The male (homosexuals), female (lesbians), and androgynous (heterosexuals), the halves each searching for the half they have missed.
Finding that other person is a feeling one cannot express, it is not just lust for if it were simply lust we would have sex with whomever and nothing more would be necessary. It is a deeper feeling it is love. For we want to be with them and show affection but cannot understand what makes us yearn for it, it overwhelms us so we cannot bear to be apart and spend our lives with them to share our souls and create new life. To Aristophanes love is simply put, the desire to find one's "other half", to attach and become the person we once were before they were separated.
Aristophanes is quick to say that that we must worship the gods and the divine for if we should oppose them ever again we shall be cut in half once more to hop on one leg. Aristophanes means by this that in order for love to flourish the gods must be central to our desires, for they allowed us to exist in this separated state instead of killing us on the spot. Through the gods and the divine we can seek to find our other half and once again feel wholeness, if we are worthy. Perhaps the gods may one day see fit to reattach ourselves if we worship them enough, it is in Aristophanes interpretation that the gods are central to humans both seeking love and attaining it.