There isn't a perfect formula that can tell you how long to date before being exclusive with someone. For some couples, it feels right to define the relationship immediately, while others prefer to date casually for a few weeks or even months before committing to exclusivity. Other factors - such as timing and distance - can also affect how soon two people decide to see each other exclusively. When it comes to the difference between being exclusive and being in a relationship with someone, the lines are blurry. They're essentially just two different ways of saying the same thing: you're dating each other and no one else. Some people consider exclusivity to be the first step.