That is a theory but not always true. I'd been relatively fine for years and then circumstances put me right back where I was as a teenager. I've met a number of people on here in similar situations. I think BPD can improve or get worse....it all depends on what life throws at you. If you have nothing dramatic happen, it will get better over time. If you get involved in a relationship, are afraid of being abandonded, or adverse things happen, it will come right back. Just depends.