What is the ruling on estrangement that may lead to cutting off relatives due to personal disagreements, and is this considered the forbidden cutting off of kinship ties, especially since the sister believes she is in the right, but she knows Allah's command to maintain kinship ties?

If the sister has cut ties with her family, whom she is obligated to maintain relations with, due to what was mentioned, then she has committed a grave evil. This is because severe warnings have been established regarding the severance of kinship ties and estrangement among Muslims. Disagreement with family, if it leads to alienation, cutting ties, and estrangement, is impermissible. The questioner should strive to advise her sister to reconcile with her family and seek help by supplicating for her guidance and by involving anyone who can influence her.