It seems that the purpose of your post is to try and understanding why people might do this. I can offer you a potential reason but it’s hard to say when I am not there. I’d say they obviously don’t have enough people to talk to in their lives and need that extra attention. Generally people don’t do things like that (and ignore normal social behavior) unless they have some kind of (even subconscious) need.
That being said. It seems like you are handling the situation properly. I would say a healthy dose of favorable judgement might help to keep you calm and let it go a bit more easily.