There was a tiny bit of mocking and teasing about the cover of PRETTY WHEN THEY COLLIDE sharing cover art with a lesbian erotica called HOT BUZZ, but the reality of the situation is that there's hardly any F/F stock art available that doesn't look pornographic or like its done for the explicit (blargh) reason of appealing to the male gaze. It took a long time to find a picture where the women looked like they were portraying strength, yet devotion to one another.
The blond girl looks like she'll kick your ass if you mess with her woman. The woman behind her looks like she loves her partner and is holding her protectively.
It worked perfectly for Cass and Aimee. I have no regrets about using it and if I'm sharing stock art with another author who writes F/F erotica, so be it. Good lesbian stock art is so hard to find I'm not even sure what I will do if I write another Cass and Aimee novella.
Just a few thoughts...