"Sorry seems to be the only word." "Being in love means never having to say you're sorry."
Popular word. And its application has many different uses, it would seem. (For the record I hope I'm never in a situation that applies to the first quote, and I really do not agree with the second one!)
Being sorry is difficult. It means letting go, and usually when one is in no mood to do so. And as often as not, the other party doesn't give a lot of help in the matter.
However, the most difficult part of saying "I'm sorry" is to encounter a recipient who doesn't give a damn--and says so--or, worse, says "It's okay, I forgive you." but doesn't mean that at all.
Sorry and I-forgive-you are a couple of those damned two-way streets you hear about growing up. The ones you're expected to drive without a license.
I don't know if growing up makes it easier, but it does grant more of an understanding of the words and why they are so important. Nearly every time the phrases are used they seem to give a little more understanding, even if it's very hard-won knowledge; maybe especially if hard-won.