You'll see and hear what you want to see and hear, rather than perceiving the real truth of your relationship. You'll both idealize your communication in the beginning of this affair; you might feel as if you can talk about anything together -- as if your sweetie listens to you with just the sort of rapt, devoted attention you crave, and understands you in an intuitive way. But over time, disappointment and bitterness could set in as you both realize you don't communicate as well as you thought you did.
That intuitive understanding? You'll find it's just a series of assumptions that have actually inhibited your ability to understand each other. Feeling as if you just 'get' each other will lead to a failure to listen as carefully as you might otherwise. You may even feel as if your partner misled you or out-and-out lied to you, even though you'll both be guilty of telling each other, and yourselves, unintentional half-truths. Though the realization of just how many misperceptions exist between you could really get you down, this aspect also offers a growth opportunity. Make the effort to listen more carefully to what's actually being said rather than simply hearing what you want to hear. With time, care and effort, you can hone your communication skills and learn to see each other in a more realistic way.