Resentment can build up very quickly in families, especially if certain relatives or loved ones are treated better than others. This is often seen in blended families if parents favor some children. Kids then end up getting caught in the mistakes of adults and that affects their relationship.
This is what happened to one teen whose parents favored her stepsiblings. She didn’t want to cater to their needs anymore and put her foot down after many years of not being considered. Unfortunately, her parents did not take her side.
More info: Reddit