Most Helpful Guy
Sex influences every facet of a relationship. When it's good, it makes everything better. Good sex is like glue that holds love together. Lack of good sex is like a poison that dissolves the glue. Good sex can help overcome adversity and make challenges easier to face.
In many marriages / long term relationships women tend to stop having sex because they get busy or don't feel up to it. I don't think they would do that if they realized how much damage it does.
Money is obviously important too, but from a man's perspective, a relationship with great sex but too little money is WAY better than one with enough money but unsatisfying sex.