Pretty sure some romance mods could be made. I am curious just how deep the editor is and to what extent it will be possible to define behaviors according to time/events and other variables.
It's more than just an editor it's the very tool Larian used to create the game....what it can do is....well...everything Larian did in creating the game and then some things they haven't done. You can do anything and everything with it.
But the romance is not something that should be a mod. It was something that was specifically promised and advertised constantly since the game was first introduced.