Is it okay to go through someone's phone without their knowledge?

I’m torn because I’m worried about my teenager/partner hiding something and I’ve been tempted to check their messages and apps when they’re not around. I know privacy matters, but I also feel responsible for their safety and don’t want to ignore red flags. Is there ever a reasonable way to handle this, or should I bring it up directly even if it causes a fight?

Checking someone’s phone without permission usually makes things worse. The best approach is open communication about concerns.