I've had relationships which were primarily sexual, but they didn't last. With LTR's, it has been friendship first.
One weird thing (to keep this thread on-topic) is that, while I like talking and spending time with my duals, I don't find them instantly hot the way I do Mirage partners. This reaction might be specific to me, since I haven't read about it anywhere else. I've met some incredibly, objectively hot female duals, and I kind of do not connect their hotness to a desire for action the way I do with Mirage types. I have a more "I like you. I think we could get along" reaction to duals.