I know that Mircom3D said that just because you don't see a scene doesn't mean it didn't happen, but I don't think it should be assumed that it did. Variables might play a role later. If the cheating route is avoided entirely I wouldn't expect Anne to be cheating, but of course it would come as even more of a shock if that was the case. I get the sense that if Anne is telling the MC about her adventures, she is not engaging in off-scene cheating.
The Martin cheating scene in CH9 uses a Martin variable, but you accumulate two cheating points to get those Martin points, which blocks her from confiding in the MC. So there might be some uncertainly what she's doing when you watch the cheating porn or go the Martin shower route and do not specifically make the choice to decline swinging and then tell Anne to stay. She's not going to tell you what she's doing and you're not going to see some of the cheating scenes (Drake beach, spa). Those two scenes require very specific choices in CH8. The photo scene only requires a higher cheat score.