I feel she had recently met a new guy. The reason for this is her quote “it’s a great day to be alive”. When I’m infatuated, or recently dating someone I’m infatuated or into, I say I love being alive, I feel alive. The recent pic showing cleavage etc.
that being said, I don’t think it had to do with her disappearance necessarily. But people who have met someone new can take risks (talking to a new guy is a risk technically..when in a current relationship) or veer from their typical routine and possibly in doing so, put her at risk that she normally wouldn’t have been in (her regular lifestyle appears low risk).
I have gathered from her various SM accounts even over a year ago that she was hopeful her current bf would propose. Another reference made: she has to get through school so she can be his sugar mama someday. Maybe that evening she wished her current bf had cared about her shapchat, was feeling lonely, reached out to another guy she had been talking to and who knows the rest. I suspect she walked towards her moms after ten pm to get the car. What if she had been talking to a guy online the last few weeks who isn’t who he claims to be and something bad happened as a result. Just my thoughts