Prophet wanting to divorce his second wife
(http://en.wikipedia.org/wiki/Muhammad%27s_wives) From this source I am aware that the prophet had another wife after the death of khadijah; The women he married was Sawda bint Zama. In this source (http://www.answering-islam.org/Shamoun/sauda.htm) I found out that prophet wanted to divorce Sawda after marrying Aisha. What I don't understand is that the prophet didn't treat Sawda equally compared to Aisha and his other wives, because she was aging and he found her less attractive. Despite this Sawda told the prophet that he could have aisha on her nights as lond as he did not divorce her, because she wanted to be called on the day of judgement as his wife. If prophet is such a rightous person how can he make her compromise and treat her unequally knowing her innocence. Isn't this a wrong example set by the most perfect role model for the muslim people?