Sorry for the late reply (something has gone wrong with itch.io email notifications). As Infinite says, you must have taken too long to handle the situation, and Catherine is permanently attached to you, now. You CAN still deal with her, though.
There is a hidden character in the game (a dragon) who can reset some of the paths, including this one. He has limited uses, and can give you a bad end if you use up all the resets without becoming his friend, so be careful if you find him. Let me know if you want a hint (or if I should straight-up tell you) where you can find him.