Health – if they had been willing to get married at 28 to a girl who was 25 instead of saying she was too old for them, they would have had kids. Now they are in their 50’s and it is less likely they will have kids. If they keep finding reasons to say no to people, they will continue getting older and be less likely to have kids, and even less likely to get married at all, since most girls don’t want to marry a guy that age who has never been married.
I’m not judging (at least not the people, just their actions). I understand that people have issues and hangups, etc, and they don’t choose to have problems. I’m just pointing out that it is a problem.