Not sure what to do?

My work colleague and I went out to the movies together and both told each other we were vibing each other. We're attracted to each other, he has a nickname for me, we spent a bit of time together. We both asked each other what should we do.. the problem is we work together and if things fell a part it would get super awkward. I suggested that we remain friends and he agreed. Since then, he has stopped talking to me, he doesn't sit next to me like he used to, he doesn't message me anymore. When we have a break at the same time, he sits directly in front of me, stares at me sometimes. What do I do? I still really like him, I would be with him if it wasn't for us working together.

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Update to this... I told him I liked him, he told me that he didn't have genuine feelings for me and just wanted sex with no strings attached. I'm not looking for that kind of thing in my life. He has completely stopped talking to me and has been quite immature towards me. I'm still kind to him and I also know my worth.
Not sure what to do?
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