There are quite a number of reasons, my friend. Issues as marriage are very complicated. Many people had romantic relationships that scarred them emotionally. It is experiences like that make some people resolve to never marry. Some others settle to be single for other reasons. It could be because of freedom. We know there's a certain lifestyle that a happy marriage does not permit you to have. Some are just not ready for the financial, physical, emotional responsibilities. So, it could be for very very many reasons.