Lesbian ntr is one of those things that's barely there despite the appeal, wrote a short fic some years ago with that premise thinking that I had something good there, but it never took off, no one saw the appeal
Maybe people people don't see the appeal because they're too unfamiliar with it?
Stuff like that has happened before. I remember browsing one of the smaller chans back in 2007 and seeing someone ask for futa on female stuff, and... it got almost no replies. Some other person even commented "Man, I've been barking up this tree for so long. Good fucking luck finding this stuff". And sure enough, basically all futa porn back then was futa on futa (as far as what was available on the English-language internet anyway).
Just compare that today. Futa on female is basically the norm for futa porn nowadays.
I do remember seeing a handful of more or less lesbian NTR (as in, a lesbian stealing a dude's wife/girlfriend after cheating behind his back) stories on sites like literotica. But even then, there's not a whole lot of it. There is a
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on VNDB, but it's got only like two dozen titles even with full spoilers.
But who knows, though - a single title that catches on can cause a real domino effect.