I would phrase it as coming from a place of concern and care “I’m worried about…”. and I’d avoid being instructive such as “You need to…”.

Take it gently, listen to what they have to say, it’s likely they have concerns too but might not yet have voiced them, these things can take time - don’t worry if the first conversation doesn’t seem to have a result. Often it can be many small conversations that lead to a move to change things. Good luck, keep love in your words and you can’t go far wrong.