How come money has such a big effect on your relationship? How come it is one of the major cause of divorce? How come it can be so difficult coming to an agreement with your partner on who spends how much on what in your household?
The main thing to remember is that most matters concerning money in a relationship are not really about money at all! When a couple seems to be having a conflict or difficulty over budgetary matters they are actually trying to reconcile their different value systems that they have brought into the relationship. These values give us the importance we place on buying good and services and how we save. She places a huge emphasis on appearance, romance, security, and planning. He places a bigger importance on health, spontaneity, and academic excellence. She wants to spend only when they have “enough left over” and when she does spend, it goes towards an evening dress,  a romantic escape, and a better looking home. He spends the moment he gets the pay cheque on “important” things like gym equipment, better schools for the children, and a  surfboard. Marketing people have known for years that  our basic motivation to spend is not directly related to the product we buy but rather to the feeling we imagine that product will give us.
These values come primarily from our early home life,what we have read or seen, and people we have met who have influenced us. We bring these values into the  relationship often thinking our partner will share these values exactly, and when we discover there are differences it can create a great deal of tension. Major decisions in our married life can be made based on values than have not be examined or questioned.
 A typical example is the decision as to the type of school your children will attend. Influencing this decision can be the priority given to higher education, the importance of religious education, the type of socio/economic group you identify with, the tradition of education than comes from your family. This schooling decision can in turn effect where you live and the affordability of your house, the budget you must meet for school fees and the type of job you must maintain to afford these costs. It even affects the type of friends you are likely to have and the lifestyle you perceive you have to live up to.
When you set out to create a monetary budget to accommodate these type of decisions it is important to realise the values that are influencing you and your partner, to honour these values,  and to re examine them in the light of your present relationship. If you can acknowledge that a decision made today about money is influenced strongly by a value brought from the past, then you have greater control in making the right decisions to achieve your goals.