It is common to have a disagreement with a partner in a relationship. In many cases, the source of the conflict or the disagreement is a difference in perception or a different memory or recollection of an event or conversation.
This is understandable as we see all experiences through the lens of past experiences. This means that two people can see, hear, or have the same event occur but walk away with a very different memory. Both people are absolutely convinced their experience is authentic, and for them, it really is authentic and accurate.
Gaslighting is a different situation. It involves the intentional manipulation of the other person to gain or maintain control of the situation. It is the creation of a false narrative to attempt to make one person look good, and the other person look bad. It is a technique used by narcissists to keep the other person uncertain, confused, and questioning their own perception and experiences. This is a form of emotional abuse, and it is both effective as well as highly destructive.
Understanding the difference between a healthy disagreement and gaslighting is not always easy, but it is possible. Often, working with a therapist or counselor is the first step in detecting an emotionally abusive or toxic relationship.