Gaslighting is a common form of abuse in unhealthy relationships. It can happen in romantic relationships at any age — teenage relationships, adult engagements, and even marriage.

Gaslighting may not happen at the beginning of a relationship. The person doing it may first build trust, which is part of why gaslighting can go unrecognized for a long time.
Studies show that gaslighting happens when people use gender-based stereotypes and other inequalities against their victims to manipulate their reality. In relationships, gaslighting is common in domestic abuse.
Gaslighting is an abusive tactic, meant to make you doubt your thoughts and feelings. It may start in small ways, then grow into a false sense of reality. It can occur in minor incidents, making it so it’s hard to notice there’s a problem at all, especially in a relationship where you trust your partner.

How to tell if someone is gaslighting you?
Coercive Control: 10 Signs It's Gaslighting | Grampian Womens Aid
10 Signs of Gaslighting Behaviour

1. Blatant Lies

You know the person is lying, often and with ease, yet they say they do not recognise this in their behaviour. You begin to have self-doubt, question everything and become uncertain of the simplest matters.
2. Deny, Deny, Deny

You know what they said. They deny ever saying it. They ask you to prove they said it. You start to question your memory. Perhaps they were right, they never said it. Increasingly you question your reality and accept theirs.
3. Using What You Love Against You

This is a manipulative tactic used by the gaslighter, causing the person to question themselves and things they hold close. For example. if the person loves their job, the gaslighter will find issues with it. If they have children, the gaslighter will make them believe they should not have had them, that they’re a poor parent.
4. Losing Your Sense of Self

The gaslighting continues methodically and continuously over a long period of time. The victim, over time, becomes a different person. Self-confidence disappears, and the victim becomes a shadow of their former self. Their reality and being becomes that of the abuser.
5. Words Versus Actions

A gaslighter will talk and talk to convince a person of their concern for them. However, their actions will not reflect the words.
6. Love and Flattery

A gaslighter will tear a person down, build them back up and tear them right down again. This abusive pattern becomes reality for the victim and the praise associated with the building back up convinces them to think the abuser isn’t all bad.
7. Confusion

A gaslighter instils constant and consistent confusion leading the victim to become desperate for clarity. As the person searches for clarity from the abuser, the cycle continues and the abuser’s power increases.
8. Projecting

A gaslighter projects their actions on to their victim. For example, if the gaslighter is a liar and a cheater, they accuse the victim of being a liar and a cheater. The person feels that they constantly need to defend themselves for things they have not done.
9. “You’re crazy”

The gaslighter knows the person is already questioning their sanity. They also know the victim is searching for clarity. Hence, when they call the person crazy, the person believes it. The gaslighter will also tell other people the victim is crazy or mad. Hence, if the victim ever approaches those people for help, they will most likely not be believed.
10. Everyone Else is A Liar

The gaslighter may tell the person everyone else is against them and that everyone is lying. Such action further blurs the victim’s sense of reality and increases their dependence on the gaslighter.
References:https://www.grampian-womens-aid.com/...ing-10-signs/; https://www.webmd.com/mental-health/...-relationships