We seem to think alike. I just published an article that may explain some part of what you have observed. I think a big part of the problem can be traced to the "dating" process, which kind of bypasses the liking between real friends and jumps right into like-to-go-to-bed-with-them.

The folks you see who seem committed to the marriage but don't appear to get along may never have established the foundation of the relationship that keeps it working in the long run, the never-ending conversation, comfortable partnership, and mutual admiration that best friends share.