For the most part we buffer ourselves from direct experience with a conceptual layer that creates both a sense of identity and a degree of predictability and control. But this buffer also dampens the quality of experience and we end up carrying around this sense that things are dull and lifeless.
To bring experience back closer to the intensity we intuitively know, we often use exclusion to turn up the volume. We do this with groups, amplifying our experience of connection by believing in sameness within the group and difference without. This both reduces how many things are experienced by filtering out anything unrelated to our particular razor, and charges that which remains by making some attractive and some repulsive.
We do this in intimate relationship as well, tuning out the rest of the world when we are with our lover to create the sense that we are deeply connected with them. This is confusing at the end of a relationship when something we felt to be eternal and indestructible, the actual energy of relationship we know innately, disappears as if it never existed in the first place. It is actually just that particular filtering out that dissipates leaving us with only the empty props of our pretending.
Of course there is nothing actually wrong here. The stark separation we fall into when our illusions dissipate is pretend at a deeper level, part of the veil that is the container for the human experience. The collapse of apparent connection is extremely helpful in rediscovering the actual state of connection that underlies all of being.