Foregone conclusion

In the first episode, Noah breaks up with Rebecca because she snooped around and found an engagement ring he had hidden and she started wearing it without giving him a chance to propose, taking their marriage as a foregone conclusion.

[…] [Sam] Altman had made each of OpenAI’s decisions about the Microsoft deal and GPT-3’s deployment a foregone conclusion, but he had maneuvered and manipulated dissenters into believing they had a real say until it was too late to change course.