I know there are cases out there where a pwbpd splits someone to the shadow realm, the point of no return. But are there any examples of someone getting split to all white without the chance of going black?  

The only thing I can think of is if a person died in the idealization phase and the pwbpd immortalized that person in their head as a god...but then again a pwbpd is also equally capable of hating that person for leaving them to soon.