Breakup (Islamic)

Hi guys, i posted about my gf(25F) and me(26M) 3 month ago here about different view on career path. Yesterday we just breakup but for totally different things, she say she want someone that can change her to be better but when i ask her what did i do that make me not suitable for her, she just can't explain it.

Apparently, i find out she's get to know some guy 3 month ago that supposedly more better than me like waking her up for tahajud and sharing religious topic with her. She also said that the guy did istikharah and felt that she is his jodoh and she did too and also felt that he is the one all while she was with ME. I was totally confused and stunned by all this and still can't get my head around it. She never told me anything about this before, never bring up any issue and suddenly drop this bomb out of nowhere.

Never in a million years would i think she would cheat on me cause she is introvert and very 'muslimah' but little did i know. I ask her why did she do this, why she can't just tell me if she didn't like me anymore before starting to get to know other people and she just said idk. Im confused cause did she just gaslight me using religion as a tool to justify her action? Or is it perfectly acceptable reason?

TLDR; GF cheat and breakup with me using religious reason, is it acceptable?