Why do I feel bad? 😔

Over the past months, one of my closest friends started distancing herself from our group. Little by little we could tell that she was drifting away from us. And later I learned that she has a new friend group, which is fine, I didn’t take it as there being anything wrong with that. But as time went on, she ignored us completely… And we’ve supported her through some of the most difficult and painful moments in her life… I don’t think I did anything wrong, then why do I feel so guilty??

My question is, is it worth fighting for a friendship that you feel is lost? 🙁