I've played a range of characters based on their attitude toward sex. What I usually try to do is incorporate the themes into the overall story so they form an integral part of it without taking over.
It essentially depends on the game as much as anything. For something like the World of Darkness where generally speaking everyone is broken in some spectacular fashion (former abductees, undead leeches, etc) it's fun to create equally spectacularly dysfunctional relationships, and for that such elements work really well because what else have these people going for them? While you're struggling to hold onto what's left of your humanity you might as well get a short reprieve between the sheets where something feels right.
However when it comes to actually roleplaying all this the act itself is boring to me since describing the mechanics of thing A going into thing B get awfully repetitive after a while. The setup itself though can be fun since all that other stuff comes into play big time because it gives these characters depth; sure, my guy really wants to stay grounded to keep the Brood out of the city but he's also crippled by jealousy about his girlfriend who took a couple of sips out of the other guy's veins, or yeah, my werewolf happens to equate 'courting' with 'hunting' and he's stalking the hell out of the girl who smiled at him that one time in the subway.
Playing such obsessions out appeals to me, as I've no interest at all in healthy IC relationships. Those can't go anywhere because what's left for the PCs to do after they've hooked up and everything is working out just great for them? It's way more interesting to burden them from the beginning with what comes to irreconcilable differences then watch as everything they try to build based on attraction or lust comes apart at the seams again and again.
In that context I don't much care how deep the dysfunction goes. It's all IC, they are all monsters, and there are no victims. It's not like a happily ever after is in the works for them.