Marring someone with the expectation of changing him/her is about like jumping out of an airplane without a parachute. The chances of landing are about the same in both cases.
As risky as it is, many girls and boys are still willing to gamble on their future happiness by marrying someone in the hope of changing him/her. A girl may argue with her, “I know Iyke drinks too much and chases other girls, but I think he will change after we are married.”
This is wishful thinking and it is 100% wrong. You do not change a person’s basic nature by marrying him. If there are problems before marriage, they will likely be worse after marriage.
How to avoid this pitfall: don’t expect to change a person after marriage. What you see is what you get.

7 trying out sex before marriage: trying out sex before marriage is often presented as a very reasonable course of action. A boy will say, “You wouldn’t buy a pair of shoes without trying them, so why marry without first of trying out sex”?
There are several reasons why the “try it out first” the idea is not good. Marrying someone cannot be compared to buying a pair of shoes. A woman is not to be thought as a piece of merchandise to be “tried out,” but a life partner to be loved and cherished. She is precious and priceless in Gods sight, and she ought to be the same in your sight. Remember, your looking for a life partner not just a sex partner.
Furthermore, a before-marriage test of sex is not a valid sample of what sex will be like within the marriage.
How to avoid this pitfall: don’t accept the foolish “try out sex before marriage” idea. If you have real love going for you, you don’t need to worry about your sex life being good. It will be!