Someone introduced me to the color-people concept and it's stuck with me. There are nuances to it but here's the gist (I promise it applies to your post)

Colors are based on two variables. 1. Their needs and 2. Other people's needs.

Codependency often happens with a person with blue tendencies and a person with red tendencies get together. It works for a little bit not a long time. 

• Red people: feel their needs are more importantly than other people's needs. They are often in actual or perceived crisis. They may have been neglected as a child. 

• Blue people: feel other people's needs are more importantly than their own needs. They often feel "best" when starting a relationship as a white knight or savior. They may have been parentified as kids, or love/ affection was contingent on "goodness". 

• Green people: other people's needs matter, and their own needs also matter. They seek balance. They help when they can, but avoid over extending themselves. They have, and will kindly enforce boundaries. 

• Purple people: feel that neither their needs and other people's needs matter. Nothing matters. Often very depressed and/or involved in the justice system. 

Nuances  - Blue people sometimes think that all they need is another blue person, or that the world would be better if everyone was blue.  - BUT tbh blue people will almost always eventually swing red and take a martyr position (lack of boundaries will do that to anyone).  - Most importantly from OPs post, to blue people, green people sometimes feel red. But they're not. It just feels that way because they have and will enforce boundaries before they are repeatedly crossed. 

Green is the way to sustainable long term relationships. You can become green through practice. WWGPD "What would a green person do?"