Psychological + Financial
As in your initial example, you get close to a lady, exchange numbers, share personal info/stories, etc. One day she asks to borrow some money. You're hesitant but she gives you a convincing sob story. You lend a small amount with the expectation that you may never see it again. She ends up paying you back so you trust her more. Some time later she asks again, you lend again, she pays back again. Then she goes for the big score. More elaborate sob story, larger monetary request, yada yada. You're hesitant about the large amount but she talks you into it, then she asks for even more money and you put your foot down. Then she ghosts you.
This is all hypothetical BTW