I think we might be surprised because like it or not, despite the sexual nature of the relationships he has forged with each individual person. Especially in the love route, you can tell by his words that he genuinely does care about each of them. If you need examples, look towards when Joo Dee was kidnapped and how he reacted when he found out they hurt/tortured her. Or when Azula has a change of heart and you help her grow to be a better person and she is willing to rule the fire nation with you as equals or as a secondary. I can think of several more, but I only pointed that out because I believe love goes beyond just the physical.
An its quite apparent given the nature of the conversations that he has with said people. Yes, he loves sex and having sex with said partners. But there is development and growth there that took effort and hard work and was not something that happened over night. Those moments will be deeply treasured and appreciated by them whether they are young or old because it was something that did happen and that played a significant role in their lives.
