In a healthy relationship, partners naturally try to be there for each other. In the mind of a Disordered Individual, you are there to serve their own needs and your needs do not matter.
Video is courtesy of the Be The Light YouTube channel
In a healthy relationship there can be Open Dialague between the two partners. In a relationship with a Disordered Individual their monologue is what is important. They do NOT care to listen to what you have to say.
I came across a great article which discusses what I would call 8 Red Flags to watch out for.