We had no children but all of our friends and siblings who have kids divorced. I am not assuming that the kids are the cause of the divorce. However, after talking to them and seeing how much time they devote to their kids driving them here and there, shopping for them, taking care of them, etc., I can see where it would affect a marriage. Their marriage is no longer the focus of their lives, their children are. Children often cause arguments on how to raise them, who drives them where, who gives them permission that the other spouse dose not agree with, etc.. Then there is the way they drain you until you are exhausted by the end of the day and too tired for sex. Husbands start to view their wives as mothers, and wives view their husbands as fathers. Kids take priority and the whole dynamic that existed pre children is drastically changed.
All of my friends swore that having kids would not change their lives but we all know how they were very naive. As a childless couple it does get annoying to visit friends or go out to eat with them and listen to how smart their kids are and how they are winning trophies for participation in every sport they play. Every child must be very smart because I never hear a parent say that their child is dumb.
Obviously people must have children and they do bring joy to most parents but there is no doubt that they also can bring stress and strife to a marriage too as much as financial difficulties to. The more areas of potential problems and stress you have in a marriage, the more your marriage is at risk. We neither had children or money issues in our 44+ year marriage which allowed me to mover as many at twice in one year to further my career which is why I make good money. No worries about school for my kids. Let's face it, kids coast a fortune to raise and put through college. We had all that money to spend on ourselves to provide us a lifestyle most would envy.
Naturally our friends with kids talk about all the emotional benefits of having children provide. I understand that but you cannot miss what you never had. Plus we find out dogs to be enough to take care of our emotional needs.
I am all in favor of people having kids since I do not wish our species to die out. I do have nieces and nephews as well as god children to play with as they were growing but giving them back to their parents was enjoyable too.
You can look at us childless couples the same way you look at a Prius owner, we are not contributing to over population.