So it should have been right for Joyce to tell Buffy "I visited Angel today and I told him to make sure you two think about the future".
You do know that Joyce didn't say "Angel, I know you care about her, break it off".
Angel has yet to get the dream of Buffy in a wedding dress before bursting into flames.
I can understand where your coming from though with she was an adult and she should make decisions, but my counter point is I felt in that episode timeline, she wasn't emotionally ready to think like an Adult as she was completely clouded in decisions with Angel. Again referring to how she handled the way the two broke up and trying to hang on to him.
Anyone who disagrees with Joyce HAS and I mean HAS to Disagree that Buffy was right to keep Angel a secret from the Scooby Gang. They were completely unaware until Xander spots the two and the truth comes out. If keeping secrets is a bad thing, well Buffy did the worse, especially on Giles because Angel did torture him etc.