Why is he all of a sudden ignoring me after trying so hard to get me?

My coworker said he was happy to see me one day.
He also told me that I smelled really good. I sit at the front and he works in the kitchen.
I have seen him compliment other coworkers but more brotherly.
He hugged one who’s in her 40s because she had something going on with her mom but it seemed brotherly.

Once I told him I had been looking for him and he was like “we’re you?” Kinda flirty.
He asked if I had plans for the weekend and I told him I was hanging with my dad for Father’s Day. He said he was going to the mountains with his girlfriend and her dad and he took forever to say girlfriend. Then we both kept saying “cool” and he lingered and there was a weird strong sexual vibe. There was a bug and he tried to fake scare me by pretending the bug was near me.

I was stressed and he told me I was doing amazing. He had to train a girl and they came to my area. I saw them but was already rushing to go home. She came in the bathroom and when I came out he asked “what was that” because I was rushing. He followed me back out and told me bye.

Once, I was looking down and from far away he was like “hey Kathy” and he thought I was my other coworker who sits near me. we have similar hair and I was looking down. I looked up and laughed and he was like “day one without my contact lens. I was about to say Kathy looks great today.” (Me)

Later he was like “hey Kathy” to tease me.
He knows I’m seeing someone.
Other day he came over and said good morning and was blushing and it got quiet and I laughed and he asked “what?” And I told him it was awkward and he just said “ok” then walked away.

There’s a new girl in my position working on the evenings now ( she's 21 and so am I. The guy is probably early 30s ) and she’s also kinda cute and he told her hey.
The other day I asked where someone was and he told me and asked why and I was like “no reason” and he said “ok”. Today he said good morning but isn’t rlly talking to me.
Why is he all of a sudden ignoring me after trying so hard to get me?
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