Have you ever dated a woman who doesn't seem to have her feet on the ground? Or rather, has her head in the clouds?
Neither of these traits are particularly bad ones when they are coupled with other grounded characteristics, but in the case of the Princess she has unrealistic expectations of you, your relationship and her life.
In most cases the Princess feels entitled to your attention, your money and your life.
And this is an interesting situation as most scientists tend to agree that we, humans, are monogamous as long as the relationship is based on a "resource sharing" deal. You provide the safety for her and her offspring and she provides you with your gene pool future.
She expects that her needs will be met before anyone else's. If her needs are not met you may be on the short side of her anger, resentment and contempt. This type of personality is difficult to live with for any length of time. In the beginning you may be able to overlook some of her requests and temper tantrums because you have love blinders on, but after just a couple months you'll be ready to pull your hair out.
A Princess may argue with you all the time. She may thrive on the conflict because it gets your attention off of her unrealistic expectations. Don't think that if you move the relationship forward that things will get better. They won't. As humans, once we become more comfortable in a relationship we tend to take the other person for granted even more. That means the arguing gets more heated and the relationship more conflicted.
As we hate change, we won't make the effort to improve, even in a bad situation.
A Princess doesn't believe that she's done anything wrong. She usually won't take responsibility for her actions or her bad behaviour. If she treats you badly it's because you deserve it. And, she'll be sure that you know you deserve it. If you have to go through long arguments to convince her that she was wrong and you were right, this is a reason to worry that the relationship is doomed before it has even gotten off the ground.
Trying to reach her subconscious brain with rational concepts won't work!
A Princess is also not flexible. She finds it difficult to go with the flow because she wants to determine the flow. Adapting to circumstances is an important characteristic in any relationship to find success. Is she isn't willing to compromise, freaks out when plans change or doesn't understand why she isn't right all the time, there will likely be problems down the road and you should think about an early exit.
Some Princess' are stingy with their ability to appreciate what others have done for them because they expect it. Men thrive on appreciation and respect. Without it they have a difficult time expressing love. If she can't appreciate you, it will be difficult for you to maintain feelings of love over time.
If you can meet her family early in the relationship, then do it. Although normally a mark of forward movement in a relationship, it is also a good way for you to see how her parents and siblings treat her. The real Princess will be treated like a princess at home as well as expect it from others. Some families build their girls up to be Princess's because they believe that the world should see their children as they see their children - perfect. This only sets the poor women up for failure later in life as they don't understand why the world isn't treating them the way mommy and daddy said they would.