Is the meaning of the following he will not do it or he does not want to do it? or he cannot do it? something else?

She had spent the last thirty-three years building a firtress around herself. He wasn't about to break through it in the three years.

Thank you
To me, it means "couldn't".
Thanks Kangiten!
Teachers: We supply a list of EFL job vacancies
Dear Antonia,

It is an interesting question. I believe that «about to» means «going to». It is a prediction in the past.

Kind regards, Emotion: smile

I think it means " he will not do it" or in other words" he wasn't thinking about doing it."
Yes I would go along with Herr Goldmund, in my opinion 'he wasn't about to break through' means that it was not going to happen soon... if ever.
Students: Are you brave enough to let our tutors analyse your pronunciation?
My opinion is that "about to" means "going to"

It took her thirty years to build the fortress. See, it was a long period. So it is only logical that breaking through it in just three years was difficult.
To my ear, there is a secondary implication in "He wasn't about to break through ...", namely, that "She was not going to let him break through it ...".

I see something else in the phrase, based on the contrast of taking thirty-three years to build versus three years to break through. 'Wasn't about to break through' could mean nothing more than that the effort would take longer than three years, and that after three years, he was not anywhere near the point of the breakthrough. He wasn't 'about' there yet. Maybe he was halfway, though (on whatever measuring stick is applicable).
Students: We have free audio pronunciation exercises.