I think we all hold grudges at some point of our life but some of us like hold grudges hard . Im a big grudges holder ,I sometimes think about what she or he did a year ago and doubt if I should help him or her . You guys get the bad blood. So I really relate to olivia rodrigo's the grudge that was released on her sophomore album GUTS ,which I really liked . Most people assume that this song is about taylor swift after she sued her for deja vu's similar vocal scream to cruel summer (I know u get deja vu)to(its cruel summer ). The lyrics state that she has nightmares each week about a Friday in May cause she got a phone call that change her life . Trust that was betrayed ,confusion that still linger and took the thing she loved and destroyed it easily .It did a big damage on her and she hold every detail of the situation. She writes ‘my undying love now I hold it like a grudge’.I think she is definitely talking about taylor cause she was obsessed with her and then she went silent. The lyrics also states “u build me up just to watch me fall “ which is because olivia was a huge swiftie and often gave credits to taylor as a big inspiration . Ultimately I loved and completely relate to this song .