It is not gossip to share with a trusted friend something you have personally been through in relationships.
It is gossip to try to guess the meaning of things about other people that you do not have direct interaction with or have seen for yourself.
Making judgments based on prejudice toward a person because of personality, their own jealousy, or boundaries someone has set, is sinful.
If a narcissist is offended by boundaries or someone who will not bow to their will, they will judge that person as all bad. If someone does everything they like they will be judged as all good.
Narcissists cannot ever see a whole person, they only see "all bad" or "all good." The judgments are based entirely on whether or not they are elevated in the eyes of those they judge.
One of the things the narcissist hates the most is when someone thinks for themselves, those who cannot be manipulated or intimidated into submission by the narcissist.
The narcissist is all about control. If they cannot control you through lies, manipulation, intimidation or mocking, they will attempt to control how others view you.
If they cannot get you to feel hurt by their antics they will employ others through gossip to hurt and reject you. Their goal and their aim is to cause you to have a meltdown, in their mind proving you deserve what they dished out.
If the narcissist can get you to respond badly to them and others they can ruin your reputation. It doesn't matter if they started it or not, they will claim you did and you will not be able to prove otherwise. Any attempt to prove otherwise makes the target look crazy, this is the goal of the narcissist.
This is why God tells us to remove ourselves, the more we attempt to fix things the worse they get and the narcissist knows this.
1 Corinthians 5:13 "But those who are outside, God judgeth. Therefore put away from among yourselves that wicked person."
We cannot always avoid the world, but we can and must avoid those who say they are Christians but lack all the fruit of the Spirit. The pretenders in the church are many now, more than authentic believers, so we will be faced continually with a process of weeding from our company those who cause trouble.
Trouble makers talk too much, they judge things that are not sinful and not their business while they ruin relationships through their gossip.
Trouble makers rely on their feelings and emotions, they do not seek the Holy Spirit nor do they listen to those who do.
And, trouble makers are always comparing themselves with others placing themselves as superior to all whom they judge.
Luke 18:9-14
“Two men went up into the temple to pray, one a Pharisee and the other a tax collector. The Pharisee stood and was praying this to himself: ‘God, I thank You that I am not like other people: swindlers, unjust, adulterers, or even like this tax collector. I fast twice a week; I pay tithes of all that I get.’ But the tax collector, standing some distance away, was even unwilling to lift up his eyes to heaven, but was beating his breast, saying, ‘God, be merciful to me, the sinner!’ I tell you, this man went to his house justified rather than the other; for everyone who exalts himself will be humbled, but he who humbles himself will be exalted.”