Confused

I had a girl who i had a massive crush on for 6-7 months. We used to share same class , after 7-8 months i decided to finally start approaching her , rather than direct approach, i decided to know her well first , so we became friends , had phone numbers , even got in common friends group chats , atp I was crushing hard , I was started understanding her , but one night as I was just going through few common frnds we had. I found a senior guy from her class. And I found she actually was his girlfriend (we both are freshmens in clg while that guy just graduated from clg as our first year came to end).

I was devasted but my thought process was , she's perfect one , but not the one for me *** , I moved on that time , it's been 4 months now for that , we both are in same class for our second year ,I see her daily ,but I stopped interracting much ,bc there's nothing to , I don't wanna be in frnd or bro zones.

But from some week in past , I've found myself disliking her for some reason, idk why , but randomly I started not liking her , there's no jealousy or anything in between but then why am I hating on someone I have nothing to do with ? Is this common with everyone? Yes I don't have any feelings rn for her , even she gets single , idk i won't even try to hit on her.