<human>: In the company I (27m) work for, we have kind of a flat hierarchy. The teams consist of developers and a product manager (32f).

So since the project is not in the middle of some adding some big features, I was thinking about taking 1 week off and told the CTO 1 week in advance and he said it was OK. After that, during the lunch break, I mentioned that "I was **thinkining** about taking one week off work" and she got very, very upset (I think I started seeing fire in her eyes). She started saying that that is too spontaneous and that I can't just decide to go like that. 

While she is not formally my boss, she is the manager who approves all of my work, so I knew that confronting her could make my life much harder after that. So I cancelled all my plans and everything.

Now I would really want to go on vacation but I don't know how to bring that up with her without future consequences. I am afraid that she is feeling hurt by the fact that in the company she is not involved in the process of deciding who goes on vacation when. To me it looks like she feels left out.

But I really need an advice on how should I talk to her about this? I am afraid that if I use "wrong words", she might get even more upset and permanently turn against me. I would really want to stay friendly but I don't know how to put it.

I would like to say something like: How much time in advance would you like to know when someone would like to take days off work?

Can you condense the text into a few key points?
<bot>: Product Manager got upset that I was thinking to take a week off work and telling her 1 week in advance (previously approved by CTO). Now I don't know how to ask for vacation without making her more upset.