Maybe this isn't the case with you yet I'll share: for me I've found it is a defense mechanism. I'll use denial, telling myself I'm fine and everything else is okay, to avoid the real issue(s) on my mind so once I get to the appointment it really does seem that way to me but is clear to the counselor things are not. Basically I've made myself believe something that clearly isn't true to avoid the discomfort of sorting through those issues during the session. Does this sound anything like what you're going through?