When you hold a magnet up to a piece of iron, it takes a little while for the iron’s field to align with the magnet. Similarly, after you’ve taken the magnet away, the iron will act like a magnet for a little while before reverting to its non-magnetically oriented state. This lag between applying a force and the effect of that force is known as hysteresis.
Using an iron core in an electric motor can greatly strengthen the motor, by helping to concentrate the electric field. But the presence of iron also creates hysteresis. The iron core responds to the motor’s electromagnets not the way they are right now, but the way they were a short time ago. This can create a misalignment of magnetic attraction, which results in unwanted heat and friction. If it gets really bad, things can just stop working altogether.
It can be the same with people. We tend to respond to friends, lovers, colleagues and others in our lives not the way they are right now, but the way they were a little while ago. This can make it difficult to figure out both when a relationship is about to start and when it is about to end. For example, when we first meet somebody, it can take us a while to realize they are “interested” in us, because our entire mental model of that person is of someone we are not involved with.
Similarly, once we are in a relationship, remaining in that relationship can become something we take for granted. If the other person then starts to pull away, we might miss the danger signs.
This is relationship hysteresis: Our inner core responds to our lover not the way they are right now, but the way they were a short time ago. This can create a misalignment of magnetic attraction, which results in unwanted heat and friction. If it gets really bad, things can just stop working altogether.