and a promise I'm going to make myself...
Never to ask anyone - 'Why don't you do this or that', 'Why don't you do things like this or that?' 'Why don't you try this method', 'Why don't you shop here?' 'Why don't you go here?' and other questions in the same vein.....
We never know why people do the things they do - we don't know their compulsions, or what drives them - we do not know their very personal and special-to-them ideas - we do not know their deep, deep inner thoughts and feelings.....and asking these questions can just stir things up in their minds, and cause confusion/doubt/unrest. This is at best, and at worst they may be tempted to tell us to lay off. We really cannot, in truth, we have no right to, tell anyone what to do or how to behave in a particular situation...we are not walking in their moccasins, or living their lives.
You can give your views and opinions if, and only if asked and then too, remember they are your opinions and may not work with another personality or in other life conditions.....no matter how dear the person is or how close to you.
The only thing to do is to lend a listening ear, give your shoulder for her/him to lean on, be a sounding board, and offer your thoughts and ideas if asked. The point is to let the person know that you are around and will be around while they tortuously, maybe, arrive at their own solution/decision - and then to give them the reassurance that you will stand by them through the consequences....