Historically, psychologists have looked at introversion as the absence of extroversion. They measure extroversion, and if you are low in it, then you are considered an introvert. This perpetuates the perception of introversion as negative space, and introverted activities as not really doing anything. We need to train ourselves, and others, out of this idea. We need to start seeing doing nothing (or reading, or working alone on projects, or whatever it is we do to recharge) as activities that are as valid as any social event.
Jung was the first to propose the model of psychic energy, suggesting that for introverts, energy flows inward, while for extroverts, energy flows outward. Introverts tend to embrace this definition. It fels right for us because we know exactly what it feels like to have our energy depleted when we have sent too much flowing outward.
Hiding your introversion is a bad idea because introversion itself is not a problem. It only causes problems if different needs affect factored into a burgeoning relationship and handled with respect and understanding. No doubt introversion-related issues will come up over time in a long-term relationship--healthy relationships are fluid and ever changing--but if you start out being honest with yourself and the other person, you will have built a foundation for later adaptation, compromise, and mutual comfort and happinesses.
The introvert's dilemma is that we might not get a lot of invitations for the kind of socializing we like best--small, mellow gatherings. In other words, the kind of socializing other introverts like to do. Because, let's face it: We're introverts. We're all at home waiting to be invited to do introvert things. Which means, of course, that none of us are getting the invitations we crave. It's an introvert standoff.