If you two aren't extremely careful to be honest with each other about yourselves, your thoughts, your feelings and intentions, you'll both find yourselves utterly misled as to who your partner is and what they want out of this relationship. Self-deception is a big possibility here, but it will also be all too easy to mislead each other. Even if you never outright lie to each other, if you aren't perfectly, even bluntly straightforward in your communication, your partner could operate in a fantasy of who you are and what you're all about.
One key between you will be to make sure you put things into words, and never assume anything about your lover or the relationship itself. Even when you think you know what they're thinking, check with them, and then check again. Most of all, make sure you're not falling in love with an idealized fantasy lover that you made up in your head! If you can't seem to get a clear picture of each other, you'll have to try not to feel overly upset or disillusioned when you're confronted with the fact that your relationship is pretty different from what you thought it was.