^ When I think of it, the simplest explanation would be toys.
I mean like, this artist doesn't work with anything fetishy, and the logical explanation would be a double-sider in-between. There is weird shit on the internet, but I would say it's pushing it to default to futa before something, ya know, HIGHLY more realistic.
And of course, I think Rye and Casey's suggestion of hugging after sex should not be dismissed. Their expressions could be interpreted as either stimulated or exhausted.