I’ve been called intense on two occasions that I can think of, though I’d be willing to bet many other people I’ve come across thought it, even if they didn’t say it. The first time I remember was by my school headteacher who said something along the lines of, “you’re so intense—smile! You have a lovely smile”. I hate being told to smile, especially when they say something like, “smile, it might never happen!” It’s so rude—how do they know something terrible hasn't happened?
Anyway, the second time was when my partner’s friend said it. My partner and I had gone to his house for dinner and I was extremely anxious about all the conversation I had to engage in. My boyfriend left the room for some reason and his friend commented on how un-relaxed I looked and said I was “very intense”.
I don’t mind being told that. I am intense!