Is it common to experience deep hurt 5 months after a breakup with someone who displays BPD traits, but has not been formally diagnosed?
I don't think the diagnosis would have any bearing on your own hurt and/or the time you felt it. That said there are I am sure 100s of threads here from people who experience hurt 5 months and even 5 years after a break-up with people with diagnosed BPD, undiagnosed BPD and no BPD. I'd guess often it is worse if it was a pwBPD because of the traits of 'love bombing' you experience and more or less get addicted to that then gets forcibly ripped away. I'm coming up on 6 month 'breakup' with a likely pwBPD whom I didn't particularly like let alone love, but you'll see (if you peruse the boards a bit) I was a mess for 2-3 months myself due to the nature of the discard. So if you were in a long-term relationship and/or In-Love then it would be pretty normal to still be experiencing deep hurt after 5 months. That said this is a good board to get support and start getting some perspective on what happened, why you feel hurt, how to move forward, and how to either choose a better partner next time or to change some of your own behaviors next time. I promise it gets better and you can even turn it into something positive. That isn't Polly Anna Feel Good advice it is from someone who has lived it too... .