He slowly started to understand what went wrong in his marriage the last time. He did not step up to understand Helena. So, that imaginary line was never erased.
As Vincent said, he should help Helena erase that line and even join her on the other side of the line, keeping the entire world outside the line.
But now, he understood that he never had done that. He was among the entire world outside Helena's line.
It was his mistake for not trying to erase that line.
Vincent just said that Helena was trying to be a good partner in their marriage. Helena was the same in his past life as well. So, she had tried to get together with him. It was he who failed to understand his 'mission' and failed. So, it was his fault?
Yes, it was his fault.
Vincent also said something that opened his eyes even wider.
Nothing happens overnight.
Either it be love or hate.
Either it be understanding or rift.
Nothing happens overnight.