One of the neat things about a fantasy setting is that it can allow for things like polyamory and polyamorous marriages. So, there will definitely be the option to go down that route later in the story, perhaps towards the end.Since it was brought up, any plans for how this might play out in the Open-Harem route? Seems like this route is effectively to be polyamory and while in the real world legal polyamorous marriages are only recognized a few places, I'm curious if you've given thought to the possibility in a fantasy world (even if only symbolically rather than legally).
I haven't yet decided how tolerant Vhaldrea (the country they're located in) would be towards this. Possibly, the four of them will have to go to a different country where these practices are more accepted, since it wouldn't make much sense for every country to have the same laws and social norms.