I wouldn't really care how far Sam could get in the following event. Because of me there can be a handjob, blowjob or even penetration. That one suddenly crosses every boundary, that also happens in real life.
If it's told properly, that's fine with me. But I also want to have the mixture of shame and euphoria in Sophia's mind afterwards. Because she feels guilty and regrets having cheated on her husband, even though she enjoyed the sex immensely. That mixed in with the thoughts of feelings for Sam is the fear that she is endangering the future of her family and children by her actions.
And not just in one sentence, but again and again throughout the following day. And not only: "The meeting with Sam is over, I was a bit naughty there, but now I'm going to do my hair.
I would then classify that under realism and be satisfied with the story and the event.