Do married couples need to live sexually?

What is the Catholic interpretation of a married couple's need to be living sexually if they don't feel the need for it? Let's say both of them don't feel the need to live romantically. They got to the point they are ok to live together like brother and sister. They love each other and they don't need sex. It's not an act of sacrifice or any kind of mortification, basically, they lost a desire to have sex and both are ok with it. They are both still fruitful though. Are they still required to perform sex within marriage so they can keep procreating or this is accepted as ok by the Church's teaching?