I know what you mean Beth. Some people just like the attention that "crying wolf" gives them - even if it's for a brief period of time.
But when you offer up suggestions that might mean some sort of change for them they back away - or make excuses. I've seen it happen before.
Don't get yourself all stressed out about it. If - and when - they need true help they will have a hard time finding it because nobody will believe them anymore. It's sad but true.
Save your friendship for someone who won't abuse it.....