Wife and brother in law relationship advice

Wanted to know if it’s normal for my wife and her sister’s husband to have a relationship where they are playing board games and when going to park playing hide and seek with the kids together. This is with me not being present. I don’t get on with the guy as I find him weird and I’ve told my wife yet she continues to maintain this closeness. Wife is a hijabi.

When I challenge her on this behaviour I get told to change as time has changed. She is willing to cause fights between us to protect him.

Is this normal ?