Some narcissists love to use social media to get all the attention they need on a daily basis.
Other narcissists will use Facebook and Instagram to stalk and keep an eye on you, your family, your friends, your job just so they know what you're doing.
There's a big difference between curiosity and fixation. Narcissists don't like it when they lose control of you. Having to let go was never in their plan and so they struggle with the fact that you have moved on with your life. They find it impossible to accept and will take any steps they can to keep continue spying on you which can become obsessive.
This type of behavior is not normal by any means.
These online stalkers have a miserable life with problems in their own lives that they need to face but are unable to do so. Unfortunately, they will rarely see that there is a problem with their behavior and most certainly will never seek professional help in this.
The only time a narcissist will ever engage in professional help is when it is court-ordered, and even then they have the ability to fool the therapist to sign them off from treatment.
Individuals who have moved on with their lives and are happy and content will have no desire to stalk anyone online. They have no desire to see what people who are no longer a part of their lives are up to.
Narcissists stalking of you has no time limit. It doesn't matter how much time has passed since you last had any contact with these paranoid individuals. Their crazy, insane, and disturbing behavior may continue for many years.
Most of the time this online stalking will go unnoticed by the person being stalked.
Sometimes these online stalkers do slip up and leave a footprint of their presence that you become aware of.
They may accidentally hit a like or share button, then realize their mistake and quickly try to unlike or delete the share in the hope you are not notified, but this often fails, and you then become aware that you are being stalked.
For some of us, online stalking can become something much more sinister. If it gets to that stage, you will need to seek advice and support from lawyers and law enforcement.
In the meantime, try to be as safe as possible online, keep your profile private, lock it down, and keep those little online stalkers out of your life.
Remember, sadly not everyone is your friend, sometimes when a relationship ends, "friends" take sides quietly and feed information to the person they believe have been "wronged".