Hi GS & Towrite,
They aren't capable.
I'm working on this also. Think what I have learned is that part of the They aren't capable is also our expectation that they should be capable.
Furthermore, inherent in our expectation that they should be capable, is that we are judging them in a way that does not help us: We have the expectation that they should be capable, but we find they are incapable and therefore, we are disappointed and hurt and so on some level, we judge them as "bad" people (black & white thinking?).
What I'm trying to work on is that when I decide that such people are 'incapable' , what I'm really saying to myself is that they do not meet my expectation of what they should be.
If I let go of the expectation, I let go of the judgment and I feel less pain from the way these people disappoint me.
Also, if I can stop judging other people, then I can stop judging myself and if I can stop judging myself, I can start to love myself and then feel more love, kindness and compassion for myself and for others, even those who are "incapable". Then, I feel less hurt.
This is still a work in progress.