You don't know what some situations could lead to. Even, changing our lifelong principles. All in All, it depends upon dev. If I'm the writer, I could write a pretty convincing storyline that could fit into Nora-Irene Ending. I know, you won't like my theory. But, there could be a some who want to see Nora-Irene threesome ending, and yes, I'm sure atleast they will be happy to see that combination. And it's just one of the multiple endings. And, yes, You are nit picking. There are may be one of the ending which may suit your taste. Irene and Nora, both would get their solo endings along with threesome ending. And, My theory is just my guess & speculation. Dev is the ultimate decision maker.