How to deal with insecure partner?

Every once in a while she would come up with a question such as, "do you like girls that do xxx", "does it bother you when I do xxx" and so on. After every question I would reassure her of my love, of my commitment to her, of how I wouldn't change anything of her, how I like her the way she is. However it just feels like I'm talking to a brick wall.
Yesterday it happened again, we were watching a series when she started asking questions and talking about other topics like she usually does. At some point I got quiet because I was too focused on the episode and she noticed, so she got quiet for a second too. After the episode was over she asked me if it bothered me that she talked so much. I said no, and asked her to forgive me if I get quiet cause sometimes I'm just paying attention. She instanty got insecure and said she would stop. I just wanted to watch the next episode, however I stopped so we could have a conversation in which I tried to explain that everything is fine and she doesn't need to change. We watched the next episode and she was fully quiet. Not even laughing at my jokes. After the episode ended I decided to talk to her, "hey look, it is starting to affect me when you go insecure like that, I know its normal and I do my best to support you, but you have to stop and that security has to come from you". She was quiet for a long time. After a couple of hours we discussed. She told me how she felt like in her case this wouldn't bother her, how its a small thing, how maybe I am better with someone else, how she values more the good things than the bad things. All stuff I've heard before, but I felt it was off topic. I told her "but it bothers me" so she goes "it shoudnt".
It is something I have noticed, whenever I feel frustrated, or bothered, or annoyed, and I tell her, her answer is "well its such a small thing just ignore it". For once I would like to hear a validating sentence from her. Am I in the wrong? ran out of space feel free to ask me anythign
How to deal with insecure partner?
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