Responsible Parenthood

Referencing paragraph 10 in Humanae Vitae, Pope Paul IV makes a claim about how married love are required to be aware of their obligations towards their family aka 'responsible parenthood'. "The exercise of responsible parenthood requires that husband and wife, keeping their priorities, recognize their own duties toward God, themselves, their families and human society." Basically saying that parents should have their children be one of their top priorities in life. I don't necessary disagree with this statement. It makes sense morally that two people who have children should take the responsibility and have the child basically be their top priorities in life and in order to be accepted in society. But it does bring up the social aspect of parents when one of them decides that they don't want to be one anymore or care for a child and the ones who decide to stick around and fulfill this responsibility. Aren't the ones that stay just as good as two parents? sometimes maybe even better? I believe that some parents who decide not to keep this responsibility aren't necessary bad people (depending on the situation, of course) but they probably weren't ready to be parent. The Pope doesn't really address this in the Vitae but I think it's important to point out that plenty of single parents are capable of being responsible for their children without marriage/partner, although it might be difficult it is possible. Susan Bordo brings up the idea that the useful body is oriented around the idea that we were born to procreate but it doesn't dictate how the child should be raised. Although in some cases two parents might be ideal, single parents should also be credited too for displaying 'responsible parenthood'.