reference from NM

I just have a question regarding references when applying for a new job. Is it a 'must' to give my current nurse manager's contact info as a reference?

If I tell my manager that I am trying to change my job by asking her to give me a good reference, the manager would certainly be unhappy. In case I was unsuccessful and I needed to stay on my current job, my relationship with my manager would be kinda difficult.

So I don't think I will use my NM's name as a reference, but I am unsure how this will make the potential employer feel. Any ideas?