why do female peach into politics and disappear?

Female politicians come with power into politics and then disappear along the way. Is it because political issues are meant for men who are considered to be brave in the African society? In most cases when we are still looking foward for women who have just entered into politics they just go silent. One may wonder whether does this mean that female politicians are weak or what? For example these the Zimbabwean first lady Grace Mugabe who just entered into political field some time last year has just went quiet. When she came into politics she changed many things in ZANU-PF party and exposed corrupt members. Her deeds were promising, people thought we now have a powerful female politician but where is Grace Mugabe now?