Honestly the sex scenes in this game aren't something i haven't seen all that much.

I usually just select Shadowheart and the only thing I see is this really sweet intimate moment. I think romance scenes should focus on that, some pixels going at it doesn't do it for me.

I am happy they are using mocap for these romance scenes because there are subtle gestures that most animations miss unless they put in absurd amount of time into it.

The purpose of these romance scenes aren't to be pornographic but romantic. Now take your own interpretation of what that means but whatever it is I don't think anyone could mistake it for porn.

As for the OPs situation, yeah its understandable. I don't mind the romance scenes either but I would also be super awkward to if watching something intimate like that on screen with my father.
So I understand your son's distress, I think this is a solid game to play with your son and its easy to skip these scenes.