Guy's Behavior

Why is he now going out of his way to avoid me?

So I have a guy at my new job who is super outgoing and talks to everyone and is a jokester and is really funny. He’s about five years older than me. On my first day he introduced himself to me and joined in my conversation with other people but he’s social so I didn’t think much about it. He’s come up to my desk casually and started convos and he’s really really nice and gentle with me and has defended me from another colleague and even when he asks me to do something he’s gentler. Once we almost ran into each other physically and he kept over apologizing and he’ll say something to me and then be like “sorry if that was rude” when it wasn’t. When I told him age, he was like “you’re making me feel old” and he laughed. He’s only 6 years older. We’ve had a long deep convo at my desk too about how we both moved here and didn’t know anyone and he remembered that I liked coffee bars ( which I mentioned briefly once ).
He does have a girlfriend who I’ve heard him talk about with other people. Apparently they met at our job ( way before I got there ). But she doesn’t work there anymore.
I have gotten readings about this and they have said this guy is curious about getting to know me better ( we just met a month ago ) and is kind of interested in me and physically attracted but the word “avoid” keeps coming up.
In real life I have noticed him kind of starting to avoid me. He doesn’t come up to my desk anymore for small talk and I see him talk to literally everyone else. He’s still nice but seems to be short. It kind of makes me think that I’ve done something wrong. I don’t have a major crush on him and definitely don’t show it so he couldn’t pick up on that. It seems personal and it sucks lol.
There are other pretty girls at my job / other male colleagues and he has no issue talking to them and having conversations. Why is he starting to act this way with me? Is there a specific reason?
Why is he now going out of his way to avoid me?
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