Which is only a variation on the basic idea of a harem. And his hormones do get the better of him on more than one occasion. He even talks with Saru about how adoring the idol Lunar (albeit, not the girl Runa Edomae) is perfectly okay despite having a fiance in San.
Ranma wasn't a "string 'em all along" harem show anyhow. Ranma spent most of his time running from his fiance brigade and truthfully cared only for Akane but was too tsundere to admit it.