You get separated thats fine. But dont get divorced just after you land. Wait for an year or so.
There is no rule whatsoever about this. But during renewal or Citizenship, this might become an issue. Since it can be interpreted as you were separated during application and you didnt inform only to get PR.
Again its something that hurts if you are unlucky. It's better to be safe than being unlucky!!!!
During your PPR or COPR you were given instructions to keep IRCC updated about any major changes. I am sure your final destination is to get citizenship, and once that day arrive, there will be many questions about what happened, and if you kept CIC in the loop.
Do they care, I don;t think so, but it is a matter of keeping them informed.
Parting immediately after landing I would be suspicious, so IRCC could raise some questions. !