This discussion is purely theoretical. So far, we can identify certain midos that are common to various relationships, and can be seen in the relationship to a spouse as well as children. There are many other midos that do not overlap. These are far more difficult to predict until one gets there. And it was noted that babies do not come with an instruction manual. Additionally, learning what the midos of another are is fairly difficult. We assume that we can make an assessment, and use others to judge when we collect info on a prospective shidduch. We also assume we can study the boy or girl when dating. But these are all flawed. Our true ability to assess is generally poor. The one under scrutiny will present themselves as they want you to see them – often irrelevant to their real self.
Babies bring the contrasts of joy and challenge. The novelty is a plus, and when they begin to exhibit the cute stuff we all crave, we are overjoyed. But they come with their package of difficulties, sleeping, health issues, etc. They tie one down and restrict much. We might have managed many relational things without kids. How will our psyche cope with new limitations? Predictable? Likely not.
How about fathers who are separated or divorced? Do they make good fathers? Usually yes. Husbands? Depends who you ask.
Just some thoughts.