The Queen's Invitation

Here we have Mirelia Q Melromarc from The Rising of the Shield Hero preparing for bed. And clearly preparing for something else. Is she asking the noble Shield Hero, Naofumi, to "join" her? Perhaps she's rewarding him for all his service while also repaying him for all the abuse he had to deal with at the hands of her husband and eldest daughter? I dunno about you but I'd accept this royal invitation. Would you?