The most likely reason for this is that slavery was seen as a greater evil than denying women the right to vote.
If you think about it, there is much to be said for this thinking. Of course, it is wrong for women to be denied the right to vote. However, it is not nearly as evil as the practice of actually enslaving an entire race of people. For example, lack of suffrage did not condemn white women to be sexually molested by their owners or to be sold away from their husbands or children.
Even as a modern person with modern sensibilities, I would say that slavery is a greater evil than denying women the vote. Imagine how much more people 150 years ago, who saw women as inherently inferior to men, would have felt this way. Because people would have seen slavery as the greater evil, it ended before women got suffrage.
Emancipation of the Southern Slaves came during the American Civil War. Women were not granted by law the right to vote until 1920. Emancipation of the southern slaves was largely due in part as an attempt to increase the south to preserve the union that Lincoln had sworn to protect. Although womens attempt at sufferage no doubt existed in some form throughout the civil war slavery was the more pressing issue within a "civilized society." In the society that existed men were predominately seen as those responsible for handling the business of politics as women were primarily responsible for taking care of the family and home.