The Nagging maybe a symptom of a larger problem.
Does she believe She is the most important thing to you?
If She does not believe that, the Nagging is already on "Auto-Pilot" and will be very tough to shut down.
If She believes that She comes second the behavior maybe a direct result of that feeling.
You need to make sure She knows how important she is to you if this is the case, and if She is not that important to you, it's you who may have the issues.
Sorry Ladies, it's Genetic how Men and Women handle insecurity issues differently...
Most Men will come out and just say it, Women are more Passive Aggressive and Nagging is a manifestation of it...