Idk, whether the couple broke up or not, you shouldn’t be sleeping with your friend’s exes. Thats like a bro code, right? Or even part of the code of sisterhood as well. Whatever reasons he has, he kinda brought it upon himself. Unless, you talked it out with your friend already, no fooling behind your friend’s back with their exes if you want to avoid issues.
This is why I hate FLs who think the world should be rainbows and butterflies up their butts. If the Duke and Ein become softies, other noble families are gonna eat them like a piece of cheese.