When walt is telling the story of the squid and the whale the therapist asks where Bernard was. Did Walt realize that the father didn't care to be a part of it or was it that Bernard wasn't in the picture then because he isn't his father?
Of course he's his father. Walt was just remembering a moment in his life when he was close to his mother, a moment that didn't revolve around the father.
Yeah the scene demonstrated how the moments when he had been most happy where when he was with his mother. He father, whom he so idolised, didn't feature in his happy memories.
I totally agree with both of you. However his father literally not present at the museum, could also mean that back the when he was a hotshot writer, he didnt pay that much attention to his family. Also it would be no suprise to me if he also had had affairs back then.
Also, remember, when the shrink asks "Where was your father?", he answers something like "it was a long time ago, before Frank was born". I think Walt was once closer to his mother, but when a new baby was born, she became less involved with the bigger son, and as a result it was then that Walt became closer to his dad.
This could also be why Walt was always trying to be more like his dad. Since his dad wasn't around much when he was younger, he was probably seeking his father's approval by trying to be more like him. Throughout the movie, he was constantly on his father's side, oblivious to the fact that his mother was in total disagreement. Perhaps not oblivious, but he did not want to acknowledge his mother's side. In the end, he realizes that his father is actually kind of a selfish dick. The mother is not perfect, but she's also not as bad as the father portrayed her.