Dangle the carrot then take it away?

Ok why dangle the carrot then take it away? So here goes. A guy at work and I have been talking a lot at work and conveniently ending up in each other’s office to flirt etc. One day he comes in my office and says “I almost, ALMOST asked you out for a drink the other day, but I hate to be turned down and I thought you may have been involved with someone else. (I have never gave any hint that I was). So I went with my second choice, but you were my first. So instead I asked so and so out for a drink. “ He caught me off guard by even mentioning this. So I didn’t say anything I was speechless. Now he tells me about them going out to dinner etc. and says well I’m okay if people here at work think we are dating cause you were my first and I would be okay with us dating but I already asked the other girl for drink and she doesn’t deserve me changing tongo for drink with you. So now when I walk by his area I do stop to say hi and be like normal but I know my heart has been crushed and he is dating someone else. We still talk like normal but just not flirt as much. So how to react. I’m lost.
Dangle the carrot then take it away?
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