A mistake I’ve mad lately

I’m so ashamed of saying it, but i have to face it.
The other day, I was talking to a woman and all was going great, to tell you the truth, I wasn’t trying to score with her, I’m already engaged, but I was sharpening my skills a little.
All was going fine when suddenly I said to her the most hurting thing she could hear that day, it wasn’t an insult, or a prejudice, it was simply:
“I’m only kidding”
To be exact, I was messing with her and she really was appreciating it a lot, she was having great fun, I could tell this by the way she was facing me and touching my hands and shoulders from time to time.
I told her something about her eye contact being scary and similar to that of a stalker, I was joking with her and she knew it. She did as if she was upset, and I didn’t know how it happened but I said it, I told her:
“I’m only kidding”
Her face changed rapidly and was a bit distant.
This is terrible if you are flirting with a woman, don’t ever tell her that you are kidding or joking, instead, if she asks you about whether you are kidding, tell her: no, I mean it.
Mistakes happen.
What’s the mistake you’ve made with a woman you are the most ashamed of?