One of the biggest problems in relationship is that we usually do not have a clear understanding of what we want in a partner or define clearly our expectations. Many people are so smitten by physical appearance that they pay little attention to the person’s character. The end result is that we often find out too late that all that glistens is not gold and that looks can be deceiving. So before you make the biggest mistake of your life get to know as much as possible about the character of the person you are about to become involved with. Never assume that because the person is physically attractive he or she is a perfect match for you.
Marva's Motivational Blog 
Getting into relationship with somebody who apparantly seems incompatible to you with a thinking that after marriage things will fall into place is another flawed decision couples and especially women take nowadays. We all need to understand how much can we change ourselves when we share our lives with somebody.
A bad relationship will in no way get better with marriage. People often see the signs that it won’t work out but still go ahead anyway.