Some people have a hard time apologizing. They'd rather pretend nothing happened and evade responsibility for actions that hurt someone else.
Others fudge and deliver the classic non-apology apology, which might be more frustrating than not getting any apology at all. It's usually a variation on the "I'm sorry you feel that way" theme, deflecting the wrong-doer's responsibility and putting the focus on the recipient and her flawed or misguided reaction. Ultimately — it's not an apology.
There are lots of reasons apologizing is hard, according to Psychotherapist Dr. Robi Ludwi. It's a blow to our egos to apologize, because we are admitting weakness, because we're asking for forgiveness (which puts the other person in a power position and makes us feel vulnerable), or perhaps it reminds us of being the child to a critical parent. And then there are those who are in total denial completely: if I don't acknowledge I did anything wrong, the thinking goes, I must not have done anything wrong.
As anyone who was on the receiving end of bad behavior will tell you, an apology is crucial. You can't regain trust or respect from a person you hurt if you don't acknowledge what you did, make amends, so that the relationship can move forward.