To be honest I kind of consider us separated right now but I have not fully committed to a break up. My partner does not want it to end and is adamant we should make the relationship work. She has moved to a mutual friend who has a spare room to give me space. I will not date anyone else unless I know for sure I want to break up. She will not either.
I am wondering if I decide not to break up and we work things out and resume living together, would this still mean my application needs to be withdrawn because we spent time apart for a while.
If you get back together and never mention it to IRCC, then it will be like it never happened so probably wouldn't be an issue.
HOWEVER there are 2 big areas that could be of concern.
1. It's a basic requirement of an inland app, that sponsor and applicant are cohabiting inside Canada for duration of processing. This is true even if you're a married couple, 1 person can't live in another city for work purposes even while the app is in process. Cohabitation is mandatory. So if IRCC at any time learns you are no longer living together, this alone is grounds to refuse your app. Though realistically they won't learn you aren't curenlty sharing the same home unless someone tells them, or possibly if she starts changing all her address info on government forms.
2. In order to become a PR after app is approved, BOTH of you must attend the landing interview. At this point the visa officer will confirm you're cohabiting and that you're still a couple. If you aren't cohabiting at this time (so still on your break) then the visa officer will deny your landing and basically cancel the app at this point. Also your partner may at some point seriously question their financial responsibility in sponsoring you, and at some point want to withdraw the app (which you have no control over).
It's really up to the 2 of you how you want to proceed here.