I'm not understanding exactly what Rooney has done wrong, he isn't messing you around, he isn't toying with you, there hasn't been any antics or statements going on like there has been with Torres and Fabregas. He has made his intentions clear that he wants to leave, many players in his position would have forced a move in the transfer window - gone on strike, refuse to turn up for pre-season training, that sort of thing but he is still around and it has until now been kept in house.
If he has got tired of Man United, if he senses a seismic shift in the balance of power in English football away and wants to go somewhere where he can be successful or for whatever reasons he has then that is his prerogative. After all he has already done it once, there was never anything to suggest that he wouldn't do it again. I am far from the biggest supporter of his personality and matters off the field but if he wants to leave then let him.