While mobile games like Obey Me populate the market for demon boyfriends, there hasnt been as much development in the demon girlfriend field, at least until Helltaker came around.
Helltaker is a 2D puzzle game where you play as a man who goes to hell in search of his own demon harem. Per the developer Vanripper: dont get your hopes too high though, its all tame
Source: N4G PC Helltaker Is A Free Game About Pancakes And The Noble Pursuit of Formal Devil Waifus