I wonder… She's stayed with r!Ciel the whole time of the blue cult ark, and only went back home after the truth was revealed and o!Ciel arrested, so maybe she'd stay with r!Ciel ?
But I can also see her taking her time away from him to realize she doesn't want to go through that arrangement at all anymore, after being betrayed that way and not knowing who she loves and can trust anymore. But not sure if her parents would accept it, given the implications of her marriage…

Poor Lizzie