Why do we never say what we mean?

I understand we were all raised to be polite individuals, not to upset anyone unless unavoidable, and to put other people before ourselves. I think these are all basically good life lessons... except somewhere along the way we stopped expressing ourselves completely. For example:

Polite: Can we talk?
Reality: I am REALLY pissed off and you'd better do something about it!

Polite: I see. Why would you think that?
Reality: You are being paranoid again, and aren't listening to what I'm saying.

Polite: I understand how you feel.
Reality: I will say absolutely anything to get this conversation over with.

Polite: I'm sorry.
Reality: I'm not really. I'm only saying that so you will stop nagging.

Polite: Nothing is wrong.
Reality: I'm going to make you suffer in silence until you can guess why you're in trouble.

Polite: I'm Fine.
Reality: You are in SOOOO much trouble that I can't even speak to you!

Polite: I need to be by myself right now.
Reality: I think that if we stay in the same room together for one more second, I'll throw something heavy at you. Or possibly something sharp and knife-shaped.

Polite: I'm doing my best to communicate effectively with you.
Reality: I'm so frustrated I want to pull out my eyeballs!!!! Why don't you listen to what I'm saying!!!

Polite: I think I need a drink.
Reality: I need a drink to numb the irritation. I may have two. Scratch that, I'll drink the whole damn bottle.

Who else has one?