The sin of pride and the sin of omission. Re-read the story.
Once upon a time there were different beliefs in America. The saddest thing is a lot of the beliefs in that the story really didn't change until after 1970. A woman may have not had a scarlet letter sewn to her chest, but a woman having a child out of wedlock was shunned, not marriage material, not hired for most jobs (you can't trust her), fired, disinherited and refused help from any church. Yes the beliefs did weaken slowly, but what you are reading was a hard and fast rule up until the mid-century. SO, it would be easier for someone to deny their connection, get approval and faith of all those around them (including women) if they didn't say anything. Society and beliefs terrific subject matter.
People sometime go on about the shame they carried by not acknowledging the child, but you can see that society rewards them for that silence. Keep reading and be happy for change.