I mean just not being rude, and being very easy to approach or kind in no way translates to flirting, realistically most guy do know this which tells me they are simply trying to take advantage of your more easy going nature. Soon as their attempts fail they get angry because those type of people are like that to begin with. It's never rude to set boundaries with someone upfront and if this keeps happening maybe you should see what all these guys have in common and change the type of person you talk to. I do agree with everyone else that this is largely a "them" problem and seriously sounds like they are extremely immature people, however to be fair without knowing what you do that comes off as low-ki flirting I can't be fair to say for 100%. Once you do make your intentions clear, that should be respected and if anyone is throwing a tantrum like that, they truly do have a personal issue that you'd be better off not involved with in anyway.
