"My wife might be having a baby, shouldn't I be happy?" Edward Wheeler 'Bright Righteousness' retorted.
When he first heard everyone joking, he did have a moment when he couldn't grasp the situation, but once he had accepted the news, his heart was enveloped in joy.
Isaac might be having his child.
But after the initial joy, he started to feel fear, or more accurately, he felt at a loss.
Although Zoe is his son, and it's not his first time being a father, when he adopted Zoe, he had no sense of fatherly responsibility and thought taking care of a child was very easy.
It wasn't until his marriage fell apart and Zoe developed psychological issues, and Isaac entered his life, that he slowly began to comprehend the responsibilities a father should have, and he gradually learned how to be a dad.