Come on... the NBA is a dog eat dog environment. Fans like to think of teams as families, and sometimes the vibe IS like that, but those are exceptions.
In reality, guys are in a fierce competition for opportunities, minutes, touches and shots... uncontested rebounds equal dollars and you don't steal them from older players if you're a rook... the people who are in danger of getting replaced by rookies are well aware of it and they don't like it... the vets don't "mentor" the youngins unless they know they won't play anymore anyway – they want to take their minutes. The list goes on...
Of course personal relationships sometimes spill out onto the court. These guys are just human.
Key and Hendricks are not getting systematically frozen out. I mean, recently Olynyk was accused of ignoring Keyonte and that narrative gathered some steam, until someone checked the stats and found that Kelly actually had the MOST passes to Key on the team.