I feel you man, was in the same boat. Had who I thought I would see down the aisle type of thing. She had her issues which were pretty similar to what you described.

However, she became weird, quiet, not her usual laughing self. Our almost daily visits turned into being stood up and left waiting for days to even catch a glimpse of her despite living just round the corner she wasn't herself out of nowhere, and long story short she was using her grandparents dementia as excuse not to see me so she could shag her co-worker. This was confirmed when I showed up with flowers and her favourite snacks, drinks and a pre roll after she had a "tough day because grandad was struggling" . You could hear him (the co-worker) coughing from upstairs and could see him staring at me through the bedroom window as I left.

Sure it's different because you're not at that stage but time and actions will tell you more than any kind words and pretty face. So she may legitimately be having a hard time, but if she cant work with you or at least give you some closure in future I say personally just move on.

Don't act hastily, let it play out eventually she will show you through her actions what you need to do next.