Is he into me, or just likes the attention?

I recently asked out a very shy guy at work. He said he was seeing someone else and I said that was cool but, I have caught him staring at me a lot since then. Other people too have noticed him staring at me and lingering a little longer than his job calls for when working near me. BTW these other people don't know I asked him out or that I like him. He will not start a conversation with me, but he'll talk to me if I talk first. Our conversations are short when around other people, but not so much if we are alone. I do like him, he knows that but he won't give me any indication of whether he's into me. He has only been with the girlfriend a short while. What do you think?
Is he into me, or just likes the attention?
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