Saying “it’s fine” to cover a choice you know is off doesn’t make it fine. It just makes it quiet.

Agreement can be a way of ending a conversation rather than a statement about the facts. Calling something fine when you know it is not moves it out of discussion without changing anything, and the discomfort stays, now with nobody looking at it. Quiet is not the same as resolved.

Where you have said fine and meant something else, go back once and say the actual sentence. It does not need to be a confrontation; naming it plainly is usually the whole thing.