When I was describing my dream TV show, I forgot to talk about how I wanted to work in Penthesileia into the final season.
The way I see it, Achilles is still mourning for Patroclos, and goes out riding by himself, trying to come to terms with his grief, but wearing in full armor, just in case. At one of the rivers, he encounters a bathing woman. She’s beautiful, and he “falls in love” with his usual speed, but she refuses his seduction. (Which probably just makes him fall for her harder, as that’s never happened before.) Maybe they meet more there more than once, but she’s always either naked or nearly so.
So he doesn’t recognize her in her armor and concealing helmet. But then when he goes to loot the corpse and removes her helmet, he realizes that she’s the beautiful woman he had fallen in love with at the river’s edge. That way his sorrow and regret over her death wouldn’t feel so much like necrophilia. Likewise, he’d seem slightly less out of line when he then kills Thersites over the latter’s mockery.