Guy's Behavior

What does it mean when a guy at your job has his friends guard me from associating with other guys?

I work with a couple of guys at my job and there is this guy who keeps following me around. His friends are extra nice to me and cordial, which I hardly even know or affiliate myself with them. Every time I talk to a couple of guys at my job, he befriends them and eventually tries to manipulate them in not talking to me. If I do when he is not present, his friends will block me from talking to them. It's like his friends are escorts when I am walking to the lunchroom or outside. From what I heard-not sure if it's true or not, is the guy who is messing with me is seeing someone, but flirts with my good friends who is already in a relationship. What kind of guy/situation is this and how do I get out of it. I am not interested in the guy but it is sort of interfering with working with other co-workers especially if they are males.
What does it mean when a guy at your job has his friends guard me from associating with other guys?
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