I went and looked this up awhile ago, and there is also a minor and unrelated issue, apparently, of their being based on friends of hers who are /not/ together.

Which nicely dovetails with the perceived need to not have the gayness be particularly obvious.

Fried Green Tomatoes, the movie version, was a perfect example of the latter. (My father was one of the folks who chose to see them as not a lesbian couple.)