All very strange, isn’t it?
If you take her friends and family’s insistences that she didn’t have any mental health issues and her recent planning for future events, it rules out the 3 main explanations for her disappearance.
Obviously, mental health issues are often well hidden from those that are closest, and just because the Police say there’s no evidence of foul play doesn’t mean that that isn’t the case.
Her family must be going through hell. I suppose their best hope is that she’s been having issues and took herself off. There’s still hope, and fingers crossed that it still can come to a welcome conclusion.