Yes, I have, but the sex had nothing to do with our views. We liked each other and got along well, even though we disagreed on stuff. A real relationship wouldn't have worked out because we had different views, but we knew that and were okay with it. We're still friends.
I have friends and family all over the political spectrum. As long as they are thoughtful, nuanced and not extreme, I don't really care. People are people, and more than the sum of their beliefs. Besides, sometimes when you befriend those people, you can influence them and help change their minds.