Flirting

We are not very close with him but he is very friendly to me?

we have mutual friends, but our conversation is very rare and short. However, when he spoke, he was always talking about me. but the last 2 months ago he stopped talking and keeps making eye contact with me (always). He looks at me from afar and looks into my eyes closely and does not pull his eyes away, I also noticed that he turns around and looks again and thats happened 2-3 times its kinda weird.
We are not very close with him but he is very friendly to me?
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