Aside from Cayde and his wife, maybe Shaxx and Efrideet? Shaxx clearly has something for Efrideet. Whenever she is brought into the conversation, he sounds like a completely different person. He goes from loud mouthed insulter to a quieter and more relaxed insulter. Very prominent when Crimson Days comes around because he won’t shut up about Efrideet. (And apparently he REALLY likes it when Efrideet throws him at stuff). I would also say Saladin and Jolder, but we don’t actually know. They probably had a more brother and sister relationship. Yeah, there really aren’t a whole lot of opposite sex relationships in this games lore.