Why does a guy rest his hand on the lower of your back?

So there was this guy at my job before I left that used to always stare at me and look into my eyes and hold it, he’d always find me and come talk to me and check on me to see how I was doing because he knew that my boyfriend was abusing me emotionally and mentally and is narcissistic. Well one day we were talking about something and I was walking somewhere and I noticed him put his hand on my lower back like a bit above my butt. I’ve never had a guy do that why’d be do that? Also did this guy like me cause I was always curious?
Why does a guy rest his hand on the lower of your back?
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