Guys: Is it intentional when you stand really close behind a girl? If so why and what are you thinking?

A guy from work never talks to me unless it’s about work but he will always locked eyes and smiles at me. However, when we’re in a group he will always stand beside me really close (maybe only about an inch or two separating our shoulders). When our team went to dinner recently, I went to the bar to get a drink with a girl from our team and he (with another guy from our team) followed us, he stood behind me really close so close that I can smell him but he still didn’t say anything while his friend kept on talking to us.
Do you guys think he’s doing it on purpose? If so why and what does he want to achieved by doing it?
Guys: Is it intentional when you stand really close behind a girl? If so why and what are you thinking?
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