[Pirouette]

I agree with Mads, maybe talk to some of her close friends and family about the way she acts around you. She seems very insecure for a reason and the impulsiveness(especially the shopping one) sounds like she's trying to cope with something serious whether it be overcoming suicidal thoughts or self-harm or something in the past. I would also recommend talking to a counselor about this too and seeing if they could help her in any way. From what you said, this doesn't sound like a healthy relationship and it could turn into something worse if stuff like this keeps going on. Be careful and definitely talk to someone about this who could also talk to her and help her overcome whatever it is that she is going through. Hope this helps and wish you all the very best!