I guess I am very confused and wonder if anyone else feels like this is partly their fault and partly your partners fault.
I would think it's better to say that it's partly your responsibility and partly your partner's responsibility, rather than fault. I think it's impossible in a relationship for one person to be perfect and another to be 100% responsible, or at fault if you will.
Maybe you do have some symptoms of BPD. Whether people are actually diagnosed as BPD is more a matter of whether they have enough symptoms in enough severity to be clinical.
I think you need to look at specific issues and see what your role is and what your partner's role is. Even many of the techniques for talking with someone with BPD like emotional validation and direct honesty like SET are good to use with "normal" people as well.