How you phrase a question can really change how your friend will receive it. Questions that use How, What, When and Where, can make your friend provide you with more detail, they can’t easily just say ‘yes’ or ‘no’ to these questions. Questions built using these words sound like you are interested in hearing the response.
‘Why‘ questions – questions that use ‘Why’ are a special case and should be avoided if you can. They tend to sound accusatory and ‘Why’ questions are not easy to answer as it puts your friend in a position of having to justify something, or a stance, which they may not be able to do. Often you will get a ‘don’t know’ response.
“Why are you so miserable all the time?”
This sounds like your friend’s misery is an annoyance to you. Also, if your friend is depressed, for example, and maybe still coming to terms with that feeling then it might be very difficult for them to know why they are feeling that way. They may not even be able to identify the emotion they feel as misery. They may not know why they feel the way they do or they may not be able to label the way they feel. Or worse still, they may think they are really worthless or screwed up because they have been told they are miserable. Being labelled and demanding a reason is very confronting.
Instead you could ask something like
“You don’t seem your usual self, how are things?”