You can get out by either struggling or escaping. For the best odds of success, you should get your mastery with Neko girl to 100% by gaining a full point in Vigor and Technique with her. You can confirm you have this done by checking the Predator Info screen.
Make sure Amelia isn't in a willing mood or else all attempts at escape won't work, as she will be more interested in pretending and acting like she wants it without actually making a full effort.
If the struggle button says pretend struggle, then you need to press the cramped button instead until your mood lowers enough to return it to a regular 'struggle'. From there, just spam it over and over again and you'll get out, which shouldn't take too long. Took me a bit to realize this and I spent a few in-game weeks stuck inside trying escape and ask to be let out to no avail. Thought that maybe the chat she had with Fitria when I was depressed would make her let me out but she doesn't seem to give a shit.
