Listed below are five distinct types of harmful relationships. As you read through this list, you might find that your relationship with someone contains all five characteristics, or you may identify with only one or two. Please understand that if you experience even one of these patterns consistently in your relationship with someone, the behavior will cause harm to both you and your relationship if left unaddressed.
WHEN DOES A RELATIONSHIP BECOME DESTRUCTIVE?
Keep in mind that we are all capable of doing these things. What makes these actions destructive is their repetitive pattern, as well as lack of awareness, lack of remorse, and lack of significant change. This distinction should not minimize the destructiveness of isolated instances. There are times when a single incident of abuse or serious deceit is all it takes to completely destroy a relationship, even if the offender is remorseful and desires to change. It only takes one bullet to kill someone.
Resource: The Emotionally Destructive Relationship, Leslie Vernick