How do you say a cute sorry?

Apology with Sweetness

Darling, I sincerely apologize for my terrible behavior. I promise to never act this way again. Would you find it in your heart to forgive me?

You are such an amazing partner, and it pains me to see you feeling this way because of me. I assure you, I will not disappoint you like this again.

I miss you dearly and I am truly sorry for causing you any pain.

How do you express a heartfelt apology?