I would guess that her brothers got angry because Shechem was not married to Dinah, he was a Canannite and not circumcized..
Yip....he wasn't a witness and he fornicated with her.....a double whammy!
It's a good thing the dubs don't slaughter worldly people who sleep with a dub today out of wedlock, or their wouldn't be room for them in the obituary section of the newspaper.
Oh......and Jehovah just hates them damn foreskins on men that make them look like a damn anteater's nose! He likes the turtlehead, german helmet look alot better on a guys dinger I tell ya!
Gumby