He's also probably fed up with needing to have security follow him everywhere and having him and his family attacked in pubs. [1]
[1] http://www.theguardian.com/politics/2015/mar/22/farage-calls...
[1] http://www.theguardian.com/politics/2015/mar/22/farage-calls...
Does he really believe these vicious conga lines of diversity will stop just because he quit?
It's clearly unacceptable in a civilised society.