Help

I'm looking for a manhwa, forgot the name but there's a girl that transmigrated into a book she made? And she acted like a dude then the prince or Duke or idk, crown prince, ml? Fell in love with her despite thinking she was a dude but then she was sucked out of the book but the story kept going, the ml went crazy over the years that she was gone. She came back in the book and her brother joined her that looks like the antagonist, everyone thought she was a spy or something so they were wary of her, etc.