These relationships are difficult.
https://bpdfamily.com/content/what-does-it-take-be-relationshipPeople with BPD are not emotionally differentiated and don’t understand what is theirs to do, and what is not their partner’s responsibility. Asking you to “take responsibility for him feeling not good enough” is a good example of this.
Should you try to do that, it would be impossible.
The only way these relationships can be successful is if the “non” partner becomes the emotional leader and has strong boundaries. BPD is characterized by fleeting emotions, changing opinions, feeling victimized, and projecting negative emotions outwardly. As you’ve experienced, it’s not easy to be a partner to someone with BPD.
Personality disorders are a lifelong condition. People with BPD can improve through doing DBT therapy, but only if they’re extremely committed. Unfortunately, not many are. Too many will give up when therapy touches places that are challenging and frightening.
It’s a lot to consider, but please keep reading and learning more.
Cat