Our identity is the image we have about ourselves. It helps us define the things we do, the things we don't, our desires, fears, goals, etc.

At the same time, our identity is also what others think of us in terms of the things we do, the things we don't, their desires for us, their fears for us, their goals for us, etc. These are our family, friends, colleagues, and pretty much everyone that we interact with, and sometimes even ones we don't interact with (like the collective society).

Often, these identities for us that are derived from others' expectations aren't even what the others actively think about us, but just our perception of it.

Our sense of identity then is an amalgamation of all these identities. 

When our own identity is like the Sun in the solar system and all the others are like planets, then, we have little dissonance as we are negligibly impacted by the perception of others.

When our identity is like a star in a multi-star system, then there are several identities that equally influence how we feel about ourselves and this leads to dissonance as we are constantly torn between what we want for ourselves and what we think others want for us.

And when our identity is like that of a planet while someone else's expectation is like the Sun, then we have very little sense of independence and are completely driven by someone else.