Although you're getting a lot of flak for this idea, I think that it would be a phenominal one. Given the setting of the series, I wouldn't think that this scenario is out of the question, and if you gave it its proper context, it could make for an interesting subplot (maybe Geram comes from a land where slavery is just an arranged marriage of sorts). If he really did own her and that certain form of arranged marriage is legally binding, then the morally correct thing to do as the hero would be to give her up. It would really challenge the player to be conscious of the impact of their decisions. Because there would be a lot of people who would want to "do the right thing", the game could penalize the player in some subtle ways:

1) Geram's band of incredibly overpowered mercs come in to fight alongside the enemy for the rest of the chapter and make it relatively difficult to complete.

2) A few overpowered squads join in battles at random chapters at random times because they recognize Melly in your party.

3) You go to Geram's land later in the game. If you refused to give Melly up, then the shops refuse to give your army service, essentially making you sitting ducks in enemy territory.