What is going through his mind, please help?

There is a guy at my gym who stares and smiles. I was too shy to smile back and would quickly look away. He often found me looking over. His friend would even grin in my direction on seeing me. Then the guy started to become hostile and stare at me and look really annoyed. So, I would just stare back and on one occasion, I giggled because it was so awkward. The next day he started smiling and going out his way to look over. We started casually smiling again. He was always next to me or in eye view. I was working out to some guys and looked up at another, the ‘guy’ was watching me with a hostile look. So I smiled and then went and worked out next to his friends. He would occasionally look at me with a really annoyed expression. Then I saw him the following day. He completely ignored me. His friend smiled with a knowing smile. God knows what.

Does this guy actually like me and has been acting jealous and expecting me to be more forward, as he has been the one predominately smiling, is he confused or game playing? He does seem genuinely annoyed but is so friendly with every other person. He even moved behind his car when I saw him looking at me from outside. Serious replies only. Weird as we have had minimum convo but non verbals are so powerful.

thank you ❤️

Updates
9 mo
That’s the reason for this forum to gain advice on the opposite sex. Not all men think alike and neither do women. But, we do appreciate opinions and valid input.

That very guy could be on here posting a similar question, hence the anonymity. I know he’s probably not though.
What is going through his mind, please help?
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