Belle studies. She really doesn't get as lonely as Beast - and maybe he and Chelise can fall in love if she stays out of their way, and then the curse will break and Belle can ransack the library and go home, that would be fine. She works.
Belle hands him one of the foreign language books that they never got around to categorizing, and then consults her index for which of the categorized books is most likely to contain castle-building instructions.
Eventually Belle finds something. "Here we are," she says. "I think if I do this right, I can even get it to organize the library in the process. I do need to design the layout, though, and decide what it should look like."
"No, not really," she says. "Does the size of the old castle sound about right to you?" She's gotten out a notebook and begun to sketch a floorplan.
Sketch sketch sketch. "The spell will be able to fill in a lot of little details by itself, and it'll be alive the way the old one was so it'll be easy to change. We could put it some fifteen minutes' walk into the woods and live there tonight."
"Yes, the alternative is having the wedding night with just a wall between us and Charlie," she murmurs with a nervous smile.
"You're going to have to show me how it goes," she murmurs. "I have read more books than my father knows about, but not as many as it would take to actually set him on fire with distress."
"Well," he says, "I am glad your father is not on fire, and I will be happy to show you everything I know."
Belle continues working on the castle, because if this goes on any longer they're really going to need a castle to adjourn to, and finally holds up a few pages of room layouts and notes on living-castle functionality and décor. "Good?" she asks.
"Let's go pick a spot to put it," she says, pecking him on the cheek and getting up to put the books in the bags to bring along.