I discuss this principle more fully in "Principles for Drawing Boundaries" and "What Does a Biblical Relationship Look Like?" As a quick refresher, we can "defraud" our brother or sister in a dating context by showing or encouraging a level of intimacy — either emotionally or physically — that the Bible seems to reserve for marriage and marriage only.In fact, they are usually really enthusiastic about doing so.We might even say that getting to know one another better and more deeply is (up to a certain limited point, of course) the very of a dating relationship.When two people are dating — especially when it's going well and two people are really into one another — the desire to spend more and more time together, to know each other better and better, to confide in each other more and more often and exclusively, is overwhelming.As your general comfort level around each other rises, that momentum grows even more. We'll assume, per another clear principle from Scripture, that both members of our college couple are Christians.On most college campuses, that likely puts the two of you in the same relatively small social circle.
If we act like we're married before we've made that commitment, we're defrauding (and sinning).
I don't know whether you've noticed this, but people involved in a dating relationship tend to get to know each other better over the course of that relationship.