I don't have children but I have a friend that I think regrets having his second child.

First one was a daughter and it went well enough that they decided to have a second one. This time they had a son. But this time things were tougher because his son was a bit weird and my friend is a bit weird too. Wife this time needed more help with raising this kid (because of other problems in her life) but my friend wasn't able to help. This kid annoyed him immensly. Finally their relationship ended in a divorce and first thing he did was a vasectomy. Divorce was initiated by the wife which had a great relief from peace and quiet after removing my friend from the family. He is more sour about the divorce. I think he felt misjudged. They were both my friends as a couple. Now each is a separate friend of mine.