I have been working at this place for a while now, but due to Covid/Wfh, I don’t know everyone on my floor. Generally, the colleagues are friendly, and you say hi to each other in passing/go for lunch etc. Apart from one of them. What’s weird is that he’s friendly to other people - as far as I can see but actively rude to me. Of course, you can’t be friends with everyone, and god knows what’s happening in his personal life, but it’s just awkward. For instance, at the coffee machine, he won’t say hi but will strike an overly friendly conversation with someone behind me. It’s not a big issue but just odd. I don’t care to be friends with this guy, but I wonder why people behave this way? Even if you don’t like someone how hard is to say hi!