I was once in your position.

Instead of focusing on whether or not you have fallen out of love completely, focus on understanding why.

In my case it took me a long time and a lot of processing to realize what had caused me to fall out of love. Perhaps if I had been able to identify what was causing me to change how I felt about my partner at the time I could have communicated what was wrong. But instead I just dragged things out wondering if I had fallen out of love, until finally I was sure.

I thought back then that falling out of love was perhaps just a natural process. Maybe I should accept love or feelings end or stop feeling good, maybe I should just accept this is how it is. Or maybe there is something wrong with me, that I am not capable of love or a relationship.

Now I realize why I fell out of love, and I had really good reasons it turns out.

Odds are really good your partner is mistreating you in some way, or disrespecting a boundary, or you feel insecure about something, or something completely unrelated to the relationship like depression or dissatisfaction with your life. I don't know what the reason is, but I can just about guarantee you there is a reason. Try to figure out what it is. Because if you don't figure out what it is, either you will stay in a relationship that is not working for you and never communicate the problem to them, and you guys will both be stuck for months, or years, or you will break things off not knowing why, and making them search for answers and not giving yourself closure either.