Obtuse.
I was called obtuse once when I pointed out to a coworker that it was ironic she shared her birthday with Earth day, because she never recycles. At the time (about 8 or 9 years ago), I thought it was a perfectly valid observation, made with no maliciousness. Now, I can finally see that it might have been insensitive to point out on the persons birthday, on their facebook. When I was called obtuse by her boyfriend, I looked up the word and liked the word, but felt embarassed that it was applied to me. I honestly thought she would find the shared day as ironic as well.