In a way that's true but IF you were to take Ain's best interest at heart (instead of your dick's interest), then the choice does become more interesting.
And arguably, letting Ain go would probably be in her interest over being her father's third wife.
As an aside, what I found interesting in this update is
that Igor is already married, effectively removing him as a potential husband for Ain because there is no way Zaton would settle for Ain becoming someone's second wife. And I feel that Igor divorcing his present wife is also out of character for him.
A second thought, if you let Ain get married to someone else, that would generate potentially interesing scenes where Zaton will be cucking his new son-in-law
as opposed to more "boring" scenes of Ain at home with Zaton in various positions.
Although, then again, the question will be about "taking Ain's best interest at heart".