How did you know it was time to end your relationship?

I have been feeling unsure of my relationship for awhile now. Nothing is deeply bad or wrong, I just feel like she’s not my person. I’ve been in therapy and I know this isn’t self sabotage or me over thinking. It’s my first ever relationship so I’m struggling and wanted others perspective on some questions. How did you know it was time to end your relationship? How did you know you should stay in your relationship? What does it feel like to fall out of love with someone?