A lot of the disconnect between men and women has to do with the fact that men have been socialized in a way that runs counter to the way women do things. This "masculine code" is something that women simply have to be aware of to interact effectively with men. Think of these beliefs as deeply rooted rules of behavior, part and parcel of what it means to be a man:

• Big boys don't cry: We hear it at football practice—"Get up and shake it off; that's not a bone sticking out, so get going." It takes some men a lifetime to learn that maybe big boys don't cry, but grown men do. It's an incredibly difficult lesson for us to learn.
• Linear thinking is all: Most men tend to insist on a rigid chain of logic from A to B, B to C, C to D and so on. By contrast, most women are more intuitive. They're more likely to say, "Something ain't right here," even though they may not be able to identify specific, logical steps that point to that conclusion.
• It can always be fixed: The male's reaction to conflict is usually something like "You got a problem? Here's how you fix it," whereas the woman involved may not care anything about the fix. For her, knowing that the problem has been recognized and that her emotional circumstances have been acknowledged may be all the fix she desires.
• Power + Control = Success: Men are socialized to measure their own value in terms of how much power and control they have—not how sensitive they can be or how deeply they can connect with another person.

How This Affects You
Every single way in which the world makes a man is at odds with most women's definition of intimacy. Relationships in general, and intimacy in particular, are all about taking down your defenses. Intimacy means trusting people enough to give them the power to hurt you. And that is absolutely contrary to a man's nature.

What You Can Do About It
To help a man overcome his fear of vulnerability and intimacy, you have to demystify the whole area for him. He knows that his emotional self contains information that could potentially be used against him, so you have to convince him that he can trust you with it. Teach him that when he allows himself to be vulnerable with you, he can be assured of a good outcome.

Also, you tend to get what you give. If you're open and honest, and you reveal true things about your intimate self, you're much more likely to have that behavior reciprocated than if you simply demand that he do so.