Is the stereotype of the emotionally unavailable man accurate?

My female friends and I have noticed that lately we have been meeting men who fall into the stereotype of the Emotionally Unavailable Man. This is a man who, (in the context of dating):

*actively dates women, but never seems to get very intimate with them emotionally
*wants to hang out consistently but not very often
*does not talk about his feelings for you or about most things that make him feel vulnerable
*does not make you an important part of his life

I don’t think these are bad guys, and I don’t think they’re just out for sex. We have met enough of these that I think it constitutes a pattern. So what I want to know is:

First, are we actually seeing a pattern, and there are lots of guys like this, or is it just a coincidence?

If this is a real phenomenon, the He’s Just Not That Into You theory suggests that these guys just haven’t met the right woman yet and their behavior will instantly change when they do. In your experience, has this been the case? Have you been the Emotionally Unavailable Guy, or The Woman Who Changed It All, or The Woman Who Got Really Frustrated Because This Guy Was Being So Weird?

I have phrased this in terms of heterosexual relationships because those are the only ones in which I have observed this phenomenon. I would be very interested to hear if this happens in homosexual relationships too, and if the gender divide holds up or not.