My girlfriend really needs to apply for a new job and I'm going to lock her in a room until she does so.
Who exactly is going to be the one locking her up?
I will. I will also make sure she will not talk freely with anyone
It sounds like you are kidnapping her. It is illegal to trap somebody against their will even if you don't like what they are doing.
I'll do anything to get her to quit her job.
Wanting your girlfriend to find a new job is one thing, but literally kidnapping her is illegal and horrible. Your girlfriend can make her own choices and you shouldn't be so controlling and manipulative. She is her own person who should be treated with respect.