Generally speaking, I never really had problems with other people being within a certain proximity of me. Of course, it completely depends on the situation at hand. For example, in a crowded line, there’s not really much the other people can do to make room for you, so I feel that it’s a lot more understandable for them to be close to me, despite me not knowing them. On the other end of the spectrum, there was the time I was in the school bathroom in high school, and my teacher walked in and chose the urinal closest to mine. It felt really awkward because there was no one else in the bathroom besides us, so he could have used one much further away. In fact, there is an unwritten and unspoken list of rules to abide by in the men’s bathroom. It is a sacred code that must not be broken. My teacher had unknowingly broken several of these rules.
All joking aside, it really did feel like a violation of privacy. As for someone like my best friend, continuing a conversation with him in the bathroom isn’t much of a big deal. For my closer friends, we usually group up, so it’s not unusual for them to be in my personal/social space. I’m perfectly fine with anyone being in my personal space, so long as they have business with me. If they’re there for no reason at all, then it can be a bit creepy, and I’d probably label them a stalker if they followed me without talking to me. As far as intimate space goes, that’s pretty much specifically for a girlfriend (assuming I had one), or close family members. My social space isn’t really “reserved” for anyone in particular. I can’t really tell myself to be irritated that someone is invading my “social space”. Even if they’re not interacting with me particularly, they probably have their reasons for being there, doing work or something. I’m not a territorial person, except for when I’m in my car because people getting close to my car when I’m driving is a hazard. Like if I’m trying to back out of a space and someone is chatting on their phone, less than a foot from my car. That only bugs me because I’m moving 3,300lbs of steel, and I don’t want to hit anyone with it. Other than that, the only space I consider to be “reserved” is probably intimate space.