I've had feminist friends, some of them still have slightly feminist leanings, but eventually most of them burned out on all the activism and anger they were experiencing, and/or saw the truth about the effects of feminism. One of my publishers was the biggest feminist firebrand I've ever known, and finally she found religion and said it was more beneficial for women to ditch feminism in favor of Christianity.
I think also, that a lot of feminists ditched the cause when it had accomplished most of their goals (workplace equality, etc.). Granted, a lot of them want more & more power, but most of them are just like "I got mine, I can relax now".