Can people tell if two people like eachother?

Im not sure why this keeps happening but whenever i am around this guy, people always act very strange.

Ill be doing something and if he's around, people stare and smile. I work with him so we talk a lot. We usually argue and act mean to eachother. Sometimes ill be doing something and he comes from behind and gets very close and whispers things in my ear. Usually work related or lately, he says mean stuff like he doesn't like me or to go away or stuff like that.

Sometimes ill be talking to a customer, and the minute he comes around, they will look at him and me and smile. Some days, we dont even have to talk and they still smile at both of us like if they know something. Well, sometimes when im with people, he'll come and check on me and ask what im doing and he gets close. Or he tells his customers about me or makes a joke that im all up in his space or something.

My coworkers bring him up when we talk now. They tell me what he said about me and such.

Im not sure if its just my imagination or can people really notice that i like him or something?
Can people tell if two people like eachother?
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