May be because you don`t consider making mistakes as pure right to you.
Forget about why you are saying sorry, it is probably back to your early childhood.
Just become aware of your right to make mistakes, and never apologize unless it`s a must or you hurt someone.
Practice it, it may take sometime, but you`re gonna improve within a few weeks if you start today 🙂
Though I run this site, it is not mine. It's ours. It's not about me. It's about us. Your stories and your wisdom are just as meaningful as mine.