Negotiations had come to an end, and Nelson's form (along with others) wasn't great. The captaincy was removed, Nelson could focus on his game and he put in a shift until the last game. This is to the credit of Nelson, but also Robinson who put the team before an individual.
I don't blame Nelson for wanting better opportunities or a big pay rise. Football is a short career and he has to be a little selfish in getting what he wants. Equally, I don't blame the club. We moan about 'money men' being involved in the game but then expect us to break the bank to sign or keep the best players.
Nelson was offered a very good deal but turned it down. If he doesn't get a better offer and chooses to stay then fantastic. If he goes, then good luck. That is football and no blame either way is necessary.