It's interesting that this plays over and over in your mind.
Are you trying to figure out what you did wrong?
You didn't do anything 'wrong'.
Are you trying to figue out what to change so this doesn't happen to you again?
For your own benefit, you might not have felt so embarassed if you had 'fished' for an answer to that question before you took the plunge and put yourself out there so vulnerably.
For instance, when he bought something at your counter, you could have said, "Oh, I really like that? Maybe it's just a woman-thing. Does your wife like it, too?" or some such other nonsense.
If he had any sense at all, he would realize you MIGHT be searching for something and if he any respect for everyone's dignity, he would have answered in an absolutely truthful way that would've allowed everyone to 'save face', including him.
Or you could have asked him or commented flat-out. "Are you married?", "You're probably married, right?"
I don't know why he didn't wear his ring. But anyone in customer service who takes his ring off and engages in flirty conversations is big-time suspect in my book.
Maybe he artfully 'played' you, for his purpose, which may have simply been the desire to feel like he was attractive to other women, even tho he's now married.
Without a doubt, his ego was stroked by your utterly sincere, charming and flustered effort.
His lack of follow-through (like he could've apologized for not wearing his ring and given you an explanation for an understandable mistake which was entirely his fault), but his lack of follow-through makes me suspect that he was aiming for that effect on you.
If you want to get him back, I suggest that you do a Dr. Phil on him.
"Is that really working for you? To take your ring off like that? Does that lead a lot of women to fall for your flirty ways?"
"Is that working for you? Does it improve your sales?"
"Is that working for you? I wonder what your wife would think of that."
Or, if your workmates are around to hear it....
"That's really too bad that you can't wear your ring. Do you have one of those nasty fungal infections? I knew this guy who had that and they couldn't get rid of it for years. And it smelled bad, too. In fact, they weren't even sure what it was at first and then, they finally had to amputate his finger. I feel sorry for anyone who has to go through that, don't you?"
Pick any two.
You get the idea.
Sorry for letting my nastier side come out there for a minute.
I hope it at least put a smile on your face.
One last comment. Through all of this, he couldn't read your mind or your heart.
Especially not if he really is the self-absorbed, ego-stroke-seeking drone that he might appear to be.