I do try to play things down a bit or say I'm fine on a better day (or always depending on who it is), I don't want to bore people as I've been low for so long and in many ways this is my 'new normal' so I'm okay isn't really untrue,also it takes time to trust people and know when they really want to know. With patience, hopefully your friend will learn you are a safe person and will open up some of the time. Good luck and thanks for being a good friend.