My wife and I have been together since 2005. You really need to find someone who is on the same page as you about these types of things. Arguments and disagreements about fundamental beliefs only get worse with time, not better. Once the "newness" of the relationship wears off, things you both tolerate now begin to become intolerable.

EDIT: If you do leave her though, Id be careful about not making it an issue of how she voted. You will ruin any possible chance of her ever coming around to conservatism in the future.