My favorite Pastor on the radio Bob Coy (Ft. Lauderdale area, I get it over the computer) did a series on the different types of love (eros, philios, agape) that was excellent. So did my local pastor (at the time) in Kansas City.
So many affairs stem from the eros love, it feels so good, so exciting. But the long-term love means having that agape, "I will wash your feet"-type mentality. At least, I think so.
