P.W.
The concept of "settling" implies there is someone better out there for you. Is there? Is there such a thing as perfection? There are many people you could have married. All of them have traits you would dislike, eventually. Is there someone more compatible somewhere? Probably. Would you find him? Not necessarily.
It's all about making a choice, and sticking to it. Often we make that choice for a reason, the main one being that we are ready to have kids. I know one thing: I had the perfect kids, and they are the kids I was meant to have. So I wouldn't change one thing that led to their creation. And because I want to have a real, extended family, not some confusing mix of step-this and step-thats, I am committed to staying with my husband, and I don't give words like "settling" a moment's consideration.