What does gas lighting mean
It's an attempt to manipulate someone in to questioning their own reality by lying, attempting to change the facts of a situation, or superseding someones feelings or emotions
Example 1:
Person A: I'm upset about what happened.
Person B: You're not upset youre just tired. Let's go get some rest
In this example Person A's emotions were overided by Person B. As Person B told Person A how Person A was feeling (something only mental health pros are qualified to do, and even then is a something they are almost always taught never to do). Then Person B told Person A what to do next so that their feelings wouldn't be discussed.
Example 2 (more relevant to the pod)
Person A: (After catching their partner sleeping with someone) Why were you cheating on me?
Person B: I wasn't cheating on you, you need to do some healing. Am I not allowed to have female friends?
Person B is telling Person A what she saw with her own eyes is false in an attempt to make her feel "crazy". He also told her she needed help and implied she was being irrational despite the fact that he was disloyal.
The purpose of all of this manipulation is typical control, avoiding accountable, and/or dominance of another person in a (Romantic, platonic, or business) relationship or situation.