Money plays a very important role in a relationship because love alone cannot sustain a relationship. There are two persons involved and these individuals have wants and needs. These can't be achieved without money. But it is also important to point out here that money shouldn't be the determining factor in a relationship. Love should come first before money. Both are crucial for a healthy and beneficial relationship.
Just as oil is to an engine, so is money to a relationship. Even as an individual, you need money to execute some plans... In every relationship money must be involved especially to carry out some projects and run some expenses.