(Forgive me for such a long reply)
Probably because rinny tried to betray the queen. (Dalogue reference to the queen's dream quest). It's always common sense to not defy royalty so maybe the queen gave rinny some kind of punishment per her disobedience. As far as I know, for succubus, their queen is basically their "god" in a sense, this is further solidified when you accept the queen's love, she said "all succubus will return to her after their death" or smth.
But instead of straight up killing rinny (cuz that would be boring) the queen gave her a second chance (Again, dialogue reference to the queen quest) which she accepts and thus, yandere rinny was born!
As to why the queen gave rinny a second chance, she probably saw that rinny has such strong bond between lust so she puts us in the dream trial and so on.