An unhealthy relationship is a relationship where one of the partners if that relationship treats the other in a bad way, by abusing them emotionally, physically, and brings down their self-esteem.
Each relationship is different, and the signs of an abusive relationship can differs. But all of these behaviors are ways that one person tries to maintain all of the power in a relationship and control their partner. Everyone deserves to be in a relationship where both people feel safe and are respected, trusted, and loved. Sometimes the abuse doesn't just come at once, it is done gradually, it can be sometimes gaslighting. They treat you bad and make you feel you are the one who is wrong and themselves right.
Abusing relationships are very unhealthy and have negative effects on the victims involved, sometimes the effects could be long term.
Some of the serious long-term effects of remaining in a dysfunctional relationship include the gradual but steady erosion of your sense of self-worth. It makes you feel inferior and ashame of who you are.
The longer an unhealthy relationship continues, the more damaging it is, and the more difficult it is to engage in a healthy one in which there is genuine love and acceptance.