Where another actress might play the seduction as a sudden switch (coy smile, dropped robe), Asuna turns it into a nervous breakdown. The pivotal scene isn’t the physical one—it’s when she sits next to him on the couch and admits, almost to herself, "I don't want to go home yet." Her eyes don't flirt; they plead . She looks like a woman who has forgotten what being touched feels like.
One point deducted because the son’s performance is wooden. But Asuna carries enough emotional weight for two.
This makes the subsequent intimacy unsettlingly believable. It’s not romance; it’s two lonely people cannibalizing the last bit of family warmth they have left.