Reminds me of what Ted from how I met your mother always said: "never stay up after 2 am".
But in this case it would be: "never stick it inside a seemingly nice orc". Shit went South the moment she agreed to Peter's plan of not telling them of their little fun they had the night before. Ohhh Pete, you my man are seriously screwed.
Let's see...
Ogre: Kouhai, workmate(?)
Elf: Loli
Human: sempai and fiance
Orc: vengeful against her own race yandere
Hmmmm we're missing: oneesan, imouto,Childhood friend,...what else is there?