Reasons for a man from work staring at me in all social occasions for over 2 years (but avoids me 1 on 1)?

What would be the reason or reasons for this type of behaviour?

I am honestly stumped, as he also seems to be avoiding being with me anywhere one on one.

Reasons for a man from work staring at me in all social occasions for over 2 years (but avoids me 1 on 1)?
Reasons for a man from work staring at me in all social occasions for over 2 years (but avoids me 1 on 1)?
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