How can I feel better about my girlfriend's past?

I’ve been with my girlfriend for almost two years now. She is beautiful, funny, kind, and just overall an amazing person who I’m very clearly in love with. There are times when it is very easy to get lost in my feelings for her, where nothing else in the world seems to matter – EXCEPT when her past relationship comes back into my mind. She was with her previous girlfriend for about two years, and it was the first girl she had been with.

Early on in our relationship she had described that it was this amazing, fireworks love that basically knocked her off her feet. Long story short, this girl suddenly broke things off with her after two years. We started dating only a few months after this occurred. Maybe a little under a year into our relationship she spoke to this girl (her ex had pretty much disappeared after they broke up) and was allegedly able to get some closure as to why the breakup happened. There are a lot more details to this part of the story, involving me being a little uncomfortable with her lingering feelings, and we actually got in some tough arguments about her ex. But time has passed since then, and our life and our love has progressed. To this day though, whenever her past relationship comes up (I can’t even remember why it came up last time – a few days ago) she always describes it in this way that it was this captivating, and exciting whirlwind romance. When she says this I can’t help but feel like she is comparing it to our relationship, and that I am either less exciting, or just more of a safe or secure choice. I’ve explained this to her, but she can sometimes be on the less understanding side, and instead gets defensive right away. All I know is that whenever I think about this I feel really insecure about our relationship. It doesn’t seem to matter what I do to try to make things more exciting, it still just never matches up to her past. We live together and are building our lives together, but I don’t want to feel like the safe choice, I want her to be excited about us.

Do you think I am overthinking this? Is there anything I can do to feel better about things? Thanks for taking the time to read!