Just to make sure I'm thinking of the same thing as you, do you mean the picture of them dancing that MC was sent while driving home? If so, it doesn't
clearly show it differently, it's deliberately unclear - looking like one thing but could be completely (or almost completely) innocent. He's got his hand on her ass as they dance, but other than that, it could be them leaning in for one to talk in the other's ear - taken as a single snapshot in time rather than a sequence or actual video, it's easy for the captured moment to look like something it's not.
Now I'm not saying I am certain nothing happened, indeed, on a particular route it makes sense that something did (even though previous choices I'd made should prevent it). I'm just saying it's not irrefutable evidence.