My Gf (F21) is giving a fuss about my (M21) ex-crushes that I had before.

Hello I don't know where to start, so I'll just type whatever comes to my head

Does having an ex crush bother anyone if they are in a relationship? I mean it's just a simple crush, and my partner keeps bringing it up on my face. I don't want to admit it, but it is starting to irritate me now. I have never failed her to give assurances, but I feel like she doesn't trust me at all. She may say she is, but her actions say otherwise. She explained her side, it's because my crushes were my friends before, and is it really a big deal? I have already moved one considering the years that have passed by. She also blurts nonstop that we are still mutuals on social media, and I also explained, why I can't just easily cut them off. We are friends, and that "simple crush" is just like a canon event among us. Even my ex-crushes dgaf that I was crushing on them in the past. Am I a douchebag because of this? I really don't know what to do anymore. Please give me insights. Thanks a lot.