When Ryan and Tatum were growing up, they were very close. But as they got older, they started to grow apart. Tatum became more interested in boys and clothes and spending time with her friends, while Ryan was more interested in sports and video games. They stopped hanging out together as much, and their relationship slowly deteriorated. By the time they were in high school, they barely spoke to each other.
There are a few possible reasons why Ryan and Tatum became estranged. It could be that they simply grew apart as they got older and had less in common. Or it could be that something happened between them that caused them to drift apart (perhaps an argument or a disagreement). Whatever the reason, it's clear that their relationship is not what it once was.