Why are guys standoffish towards me?

For some reason I feel like guys can be really standoffish or give me the cold shoulder and I don't know why. I'm not a mean person, I'm friendly, and easy to talk too. I kind of have a big personality so maybe it's too much or something I don't know I'm just confused. Also, sometimes they get really shy/awkward and it's weird. I feel like they don't want to talk to me and I feel like there's something I'm doing to make them uncomfortable but I'm not sure.
Why are guys standoffish towards me?
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