The Sleep With buttons for your companions don't take into account if you are in a location where you can't sleep. You can click the Sleep With buttons for Kiyoko at the Den, Ryn at the Palace, and Arona at the Orc Camp. But they will always show the variation for becoming the bedmate because their isCurrentBedmate() functions will always return false. Clicking the button does toggle their Frosthound bedmate status, it just doesn't show the right button/parser variation.
You could check if bedmateCurrent() returns null and not show the button or if bedmateCurrent() returns null then you just check if they're the bedmate at the frosthound isBedmateFrosthound() and then change their bedmate status there. The second option is better since it lets you set Kiyoko as your bedmate if you don't have the Wayfort unlocked. You can't interact with her at the Frosthound so you either need to use the bedmate button at the Wayfort or ask her at the Den.
You could check if bedmateCurrent() returns null and not show the button or if bedmateCurrent() returns null then you just check if they're the bedmate at the frosthound isBedmateFrosthound() and then change their bedmate status there. The second option is better since it lets you set Kiyoko as your bedmate if you don't have the Wayfort unlocked. You can't interact with her at the Frosthound so you either need to use the bedmate button at the Wayfort or ask her at the Den.