Welcome Leeuw!
That sounds like a difficult situation, but you are in the right place.
is your girlfriend diagnosed and in therapy? or are you just going off a hunch based on behavior. I will say that it does sound like BPD type behavior.
Feel free to write a long post telling us your story and history with your girlfriend so we can get some insight into what is going on.
In the meantime... .
Here is a link to explain why this keeps happening. It is called
Intermittent Reinforcement Essentially, she keeps doing it because it works. She gets what she wants from you.
Here is a quote of note from that link. But read the article when you have a chance.
Coping with Intermittent Reinforcement - What NOT to Do:
Don't make empty threats. These are the rocket fuel of intermittent reinforcement. Don't threaten consequences that you are not willing to follow through with 100%.
Don't make rash promises. Commit to doing 100% of the things you say you are going to do.
Don't repeat threats or promises. Say them once and then follow through with them.
Don't make lots of threats and conditions. It's better to have one boundary that you keep than 100 that you intermittently reinforce.
Don't intermittently reinforce other third parties. This will only demonstrate weakness.
Don't nag. You are asking to be intermittently reinforced.
Don't beg. Ask for what you want once and if you don't get it then take back your power and go get it yourself.
Don't keep feeding a machine that only pays out 90% of what you put in.
Don't build your house in the flood plain. Offers that sound too good to be true usually are.
Stop trusting your gut. Trust what works.
Coping with Intermittent Reinforcement - What TO Do:
Forgive yourself for your past mistakes and learn what works.
Hold your boundaries and keep your promises even when it feels uncomfortable. Remember that you are investing in the "next time"
Like a person walking into a casino, decide how much you are willing to lose before you will walk away.
How do you feel about waiting her out and not giving into her demands?