Why does Huck run away at Chapter 35

Huck Finn's wealth and association with the widow drags him into society: forced to eat with utensils, dress in clean clothes, and attend school. After three weeks, Huck runs away. Tom later finds Huck in an old hogsheads behind the empty slaughterhouse. Tom convinces Huck that in order to be in Tom Sawyer's Gang, the boys would have to be respectable robbers ­ high class. There could be no low characters in the gang. With that, Tom convinces Huck to return to the Widow Douglas.