Jarvan IV should have a bunch of lovers not one lover
Demacia is based on medieval Europe and Jarvan himself is a warrior prince (classified by reav3 as such) and a lot of warrior princes had two mistresses in addition to one wife. It would be unrealistic and contradictory for Jarvan not to have a harem! A lot of people think they were monogamous but it was okay to have mistresses on side. Beside so many people think Jarvan is boring and this is a taboo according to modern society so it would give him a “fault”.