I dont follow thid anime, but saw a panel about the "aftermath" did he actually have sex with her in the manga?
As far as I've seen no. She definitely tried to get him in bed with her but he flatly rejected her when he admitted he couldn't understand her feelings at all.
I'm a bit hesitant to add this to Perversion Of Canon. Obviously it would belong if it's a reference to that scene, but there's neither artist commentary nor anything in the actual gif to indicate as much; just Boss Mage riding Slayer's ChinchinmaruFuckbringer.