"Oops! Something went wrong."
"Did my last chapter confuse you? Let's provide some explanations."
"Apologies for the mistake, I am so sorry."
"I made a wrong move! Here's what happened."
"Sorry for the mishap."
"Please accept our warmest and most sincere apologies."
"Oops! ...
"Here's what went wrong".
*What I did was wrong and I am so sorry for hurting you.
*I wish I could take back what I said (or did) and be more considerate of your feelings.
*Next time, I will be more mindful about what I say (or do).
*What can I do right now to make you feel better or help our relationship?