We need to talk...
This is the phrase that puts fear in the hearts of men when our partner uses this as a way of surfacing an issue. There is a raw vulnerability we tend to feel when our partners ask us to speak openly with them. One of the most common complaints I hear is that my wife expects me to "open up and share" but I'm not sure she can handle what's really on my mind and therefore I bite my tongue in order to protect her. That's likely not a good idea because it is based on your determination of her capacity and it denies her the chance to speak for herself. It's probably smarter to assume that she can handle what's on your mind and that she wants to hear it.
What's really at work when we resist opening up is the sense of vulnerability it produces. In fact, the word vulnerability is typically missing from our vocabulary because, as men, we are made to see it is a weakness. Talk about contrast! For your partner, vulnerability simply means openness and honesty--and those are signs of strength, not weakness. But in order to avoid showing any weakness, we often don't open up to our partners about our deepest fears and concerns, thinking that we are "taking care of her" as we have been taught to do.
The problem of withholding our feelings from our partners is that it denies us true intimacy with the person from whom we most need openness and intimacy. So, as a result, we feel isolated and deprived of a closeness to which we feel entitled as a partner. But we place the blame on her, not ourselves. This almost always breeds growing resentment as the behavior continues. And our women may feel we are emotionally clumsy or distant or simply aren't willing to share.