Picture two scenarios:

1. A loving unmarried couple, regardless of gender, sexual orientation, or child bearing, lives in an affluent neighbourhood, in a rich country, have steady incomes, and decide to have a child. After ten years they decide “I love you so much. I don’t need a piece of paper to prove that, but let’s get married. It’ll be a great opportunity to connect our friends and family, and it’ll give us some legal and financial protection when one of us dies”.

2. In a poor neighbourhood, a woman who was mistreated all her life marries her high school sweetheart, who turn out to be abusive. He not only beats her, he rapes her regularly. Like too many victims of domestic violence, she’s afraid to move away. Eventually she becomes pregnant and has the child against her will.

Which of those do would produce the better outcome?

Being fatherless isn’t in itself the issue, but everything which came before to reach that point might be. There is a huge difference between not having a father because he abandoned you, or because he died, or because your mother as a single affluent woman with the means to do so decided to do in-vitro fertilisation.

I highly recommend “New Family Values”, by Andrew Solomon, to get a feeling for the different types of families which work. It goes way beyond “one mother, one father, married”.

https://andrewsolomon.com/books/new-family-values-audiobook/