Candy, to me it's relayed to stress.
Anything that gives me enough anxiety that makes me feel like I'm going to be exposed to something I'm not comfortable with is a trigger.
And I have to say, some people, themselves, are triggers to me.
I try to avoid them, I don't like to talk to them, just in case some topic might come out that I'm not ready to discus.
In my case it usually starts with that uneasy feeling, if I don’t pay attention I go straight to anxiety and “poom” trigger time~
It also seems, like the more old I get the more triggers I have.
But now that I know what can be damaging to me, I avoid them and I try to go around them.
I hope this helps~