Thanks for your input! They are on the same breaker so the neutrals are tied together.
What is the best way to rectify the problem at this point?
I had to do a bunch of rewiring for the kitchen and bathroom remodel.
Essentially a circuit come up from the basement and feeds (1) outlet in the dining room. This travels up to the attic where it feeds (2) outlets in my office, (1) outlet in the hall and the GFCI and fan/light combo in the bathroom.
In the attic I installed (3) junction boxes to allow me to isolate the bathroom on it's own circuit during the next phase of the remodel. Even with that done, the GFCI and fan/light combo will still be on the same circuit thus sharing the same neutral.