Yes, we have an issue of feeling connected to other human beings. And what a lot of ways people try to accomplish that, and not all healthy. Joining a group is certainly one, whether it is a cult or a political cause or a golf club. Another is the love relationship. We all know the pressure brought to bear on that one.
As I try to analyze this, I'm thinking we should start with admitting the need. We are social animals. In a basic, evolutionary sense, we need each other - for survival, if not company. Craving an intimate relationship contributes to reproduction. Needing to belong keeps an individual from wandering off from the tribe where it would be dangerous. I think it's interesting to consider our modern feelings in the light of ancient impulses because our emotional make-up is thousands of years behind other aspects of our evolution. We see this in other areas of course, like aggression, defending territory, etc.