I have no clinical evidence for this condition, but I see it regularly.
One person in a relationship sets their own needs aside for the other person. This person assumes the role of door mat. "Go ahead and walk over me - wipe your feet well, and I'll get myself all washed up and put in place for the next time you need me in this role!"
It is done with loving intentions and often with the logic, "I want you to feel valued. I want you to feel good about you." The logic is flawed. It doesn't work, and it generally makes the other person feel less valued. Additionally, both people in the relationship often see themselves in the role without recognizing it in the other.
"I matter" (aka "my feelings matter") communicates significance. "I know I matter. I choose to be in relationship with because you matter too." Both people matter...equally.
"I don't matter" (aka "my feelings don't matter") communicates insignificance. "I know I matter, but you matter more. I want you to feel special. Why don't you feel special? Let me try harder."
When you set yourself aside for others on a regular basis with the hope that it will inspire change in someone else, it's not helpful. If someone is willing to be taken advantage of, and they want me to join the club, I want to get distance from them.
After setting our feelings aside in varying degrees, we may hit our limit and want out of the door mat role. "I'm done being the door mat in this relationship! My feelings matter, and you've been ignoring my feelings for years! You'll never change! "
While it's great to acknowledge our significance, we can still be in the dark. Blinded by our own pride, we become certain that "I've done all I can." We move from one extreme to the other. We over-correct. It can easily slip into feeling like a victim. It's not necessary to scream, "Don't walk on me!"
Own responsibility for the choices that have been made. Your needs matter. They don't matter less than others, but they also don't matter more.