Is there a problem in expressing what we feel?

Some of us express what we feel but some of us hesitate to express what we think. This sort of difference of opinion arouse me this question. Being one human being, can we really think on behalf of others? If we do not share what we think, how can the other person know then? So why do we have problem in expressing our thoughts or feelings? Do we afraid of the other person's reaction in this very matter? May be, however, that reaction is our imagination. Do we really know the future? Particularly, when we are not enjoying our present properly (which is expressing our feelings at the very moment when we need to)
Having said that, would that be really rude to express our feeling when someone else gets offended? May be, but we need to know what they believe-in. And, for example, if we know their beliefs we may not need to pass some blind statement just to prove that they are wrong. But I dont think there is anything wrong in sharing thoughts or feelings though the beliefs are different.

When do we miss someone?

Every human being needs someone who can care and show some affection to them. Is it because, we human beings are highly depending on someone else for our emotional actions? May be...or is it because we are afraid of being alone.
Once we create that comfortable relationship bridge between us and any individual, we find it hard when we leave them. So initial pleasure turned out to be pain. Can we say that the pleasure and pain goes together? If we find pleasure on something, we feel pain when we miss that pleasure.
Things move and change in this evolutionary world. Though we all know this universal fact, why don't our mind be prepared of the pain while having the pleasure in first hand.