just say, SORRRRRRY!!!

Why people find it hard to say sorry, to apologize

The first thing, he didn't even realize he did a mistake.
That's why i am here, to tell and to make him realize that he does something wrong
Realization sometimes hard to figure for those people who have ignorance of the environment
Sometimes, we, as a partner need to let him know that he is wrong. And it all depend on the person who do mistake. Will he apologize? Or will he not apologize to you at all after you told the fact?

The second thing would be of the prestige. Because he is in the higher position, let's say a boss. Or someone who think never do a mistake and think everything would possibly okay. They won't say sorry even never think about it. Because they think they always right. it will decrease their reputation to say the word who doesn't take a long time and maybe change the mood someone or even make the person feels happy.

We as the partner in people life need to take a part to the way people behave. There will be debate, argument, temparental kind of thing but it helps to understand each other better.

Say sorry if you are late
Say sorry when you have been waited for someone who loves you for example just a minute late
Say sorry when

Say and mean it.