Anyway, I tend to go about that character by imagining what kind of woman Inziladûn would marry. I have mentioned before that I imagine Inziladun was very good at politics, if only because he was facing such an unfavorable situation from a young age. He was at odds with his father, the king, and it’s safe to assume his plans of social reform were neither popular nor interesting to the ruling class. Therefore I normally only see the possibility of him getting a political marriage: either one imposed on him by his father in an attempt to control him, or one he chose himself in order to form an alliance with a strong family (My HC for his brother’s Gimilkhad’s marriage is that it was arranged by their father, and that he married the daughter of an important (Elrosian) lord from the colonies. I need that because of some political headcanons re: Pharazôn having the support of the colonies hahaha).

If the marriage was imposed by his father, you can have his wife either leaving his side, or being forced by him to leave, once Gimilzôr dies and Inziladûn ascends the throne. Depending on how much court intrigue you want Númenor to have at this point, you can even have her be murdered by some subtle mean, like slow poison? Not by Inziladûn with his own hands, but I imagine that for something like this to happen he’d have to be unofficially aware of it; it really depends on how you want to interpret this person.

If it WAS his choice, you still have the murder scenario - by his enemies ofc - or her death in an accident… Or maybe the alliance was desirable but they just didn’t get along and she went to live on the country once Miriel grew up. Perhaps she was not into politics? But short from an actual divorce - which makes me uneasy bc we would have heard of it in canon, and I’m nothing if not a slut for most Tolkien canon - I can’t imagine her not being alive and having more impact on the story! And if she does have more impact on the story, it contradicts my beloved Miriel headcanons, which I don’t want to hahahaha. 

So that’s all I have so far!