What is my problem??

Was in a Relationship a few months ago, but my Partner ended up, breaking up with me and got into a different relationship (rightfully so). Our Relationship itself didnt last long and that was because of my own incompentence. Dont get me wrong, i am over the relationship, but i cant get over the fact how stupid i am and how stupid i acted. We loved each other, but i some fucking how managed to not make her feel loved enough. I loved her, i told her that i loved her, i bought a gift for her birthday, and met up with her 2-4times a week, but thats it! I never bought her flowers, i didnt initiate any sort of "cool" or specific romantic activity. Even worse is: I myself noticed that while still being in a relationship with her, and i even had the thought of changing it and organizing something romantic. However i never acted out on it, and i dont even understand why. I acknowledged the issue in my mind, and i would say that i forgot afterwards, but something like that cannot simply be forgotton. And it gets even worse. I also managed to disrupt like 90% of the romantic moments she tried to initiate, for an example: 'My Partner started to dance with me, and teached me at what point i had to move my feet and such. Of course i looked down on my feet like 80% of the time, not only because i was too ret-ed to get it right, but also because i was way too nervous. And you would think, that it might not be that bad now. But just like everything else in this story, i managed to screw it up even more. I disrupted our dance and said something like "oh, dancing aint my thing"... dude... i didnt even explain why i disrupted our dance, i couldve at least said, that i am too nervous to continue, and find a way to make up for it.'. Looking back at it, it really looks like an low-tier script for some sort of comedy-movie. But not from my Ex's point of view for sure, she must have thought, she got caught up in a Thriller or something.

And well thats it for the story itself, however there is one more thing. In the days after our relationship ended, i actually caught my self, searching for excuses, to justify the breakup for myself.

So if you really feel like a fuck-up, just remember me and you will know, that you didnt fuck up that bad.

Quick Summary:

"I managed to fall down the stairs, even though gravity was inverted."

Again i want to mention, i already am over the relationship, eventhough it might seem otherwise, due to the words i used. This is solely about my own (unintentional but stupid) behaviour.

Seriously now what is wrong with me? Tell me what you think, about my behaviour, and why that could have been.