Nyther's journey

I have been working in my current role for just over six years, and recently, my relationship with my manager has become increasingly strained. There’s an opening for a slightly higher position in a different department, and I’ve been considering applying. I spoke with HR to get some insight, and they reassured me that my manager's preference to keep me in my current role wouldn’t influence the hiring decision. However, I know I need to discuss this with my manager before I submit my application because HR will inform him once I do. My worry is that this conversation will make it seem like I'm actively looking for a new job, which could lead him to undermine my application or even start looking for my replacement. It feels like a no-win situation. On top of that, the position I'm interested in is one that they’re really eager to fill, which adds to my dilemma.