I have a friend who is very charismatic, overly so. He has 3 girlfriends who he sleeps with, and has somehow convinced all three of them that they are ok with this relationship. ( I don't think he talks quite fast enough to get a 4some out of them, though.)
Anyway, when we were in school, aged 15 or whatever, he was still very charismatic, but not liberal/old enough to just sleep with everyone who could, back then, people were interested in "true love" and the like.
he had about 7 different girls who were all his friends, and who were all interested in him, they all pursued him recklessly, they all fell out with each other, and that little social group effectively fell apart. When it came time to choose which High School (well, my country's equivalent of those) to go to, he chose to go to where everyone else went, and didn't tell anyone about it.
I am still good friends with him, and, though he isn't a geek, we still have bi-weekly nerdy parties with a few other geeks, where we watch anime, play DnD, LAN, etc.
By his own words, whenever we watch harem type anime, "It doesn't work like that in real life, its really shit, unpleasant and difficult."