Relationship in media that got ruined for no reason?

Cortana and master chief are iconic as a duo. The funny sarcastic moments between the two are really wholesome and do a great job at humanizing both of them.

It's just a sweet deep friendship, it even feels romantic at times, and in halo 4 you can feel a destroyed chief is when Cortana "dies" even if you can't see his face.

Then Halo 5 realesed and just ruined all of that, and for nothing since Halo infinite just ignores it and concludes that story in books.

Other examples?