When her brother is referring to her Google Maps timeline, I wonder if he's seeing 14th and Crescent as a destination, or just noting that she drove by that area on the map. The timeline seems to note when you're at a specific location (i.e. "Opera Nightclub | 11:05PM - 11:27PM"), and it doesn't sound like that happened here. I don't use that feature, so I had to do some googling to find out what information it shows.
I wonder if she ever did any driving for Uber or Lyft, especially since she hadn't been employed for a few months. It would be one scenario that might encompass multiple gas station stops a day and swinging by an area with clubs to pick up a fare before heading home. If her mother's car was nicer/cleaner/larger, that might be a reason to be driving it instead of her own. I would assume this would show up on her email, though. She does like "Drive with Lyft" on Facebook.
Her brother has said they "assume" she returned with a tall male passenger. There may be a witness or CCTV that they're not releasing for some reason, but are they possibly just basing this on having the passenger seat all the way back? I know I always keep my passenger seat fully back, unless someone is sitting in the rear.
The townhouse guy sounds very much like a friends with benefits situation to me. Late night visits, her wanting a relationship, but him not--I definitely get that vibe. Depending on his own relationship status, I could see this being an issue.
I am also local, and the disappearance and lack of coverage are very odd, but if a voluntary disappearance, it's worrying that none of her credit cards and phones have been used. It also sounds like while Jenna was capable of living a double life, if you will, she wasn't so great at being subtle about doing so, imo? She was refusing to answer some questions from her family, stealing, etc., but the questions were there, the arrest came out. A successful voluntary disappearance requires a lot of putting yourself in someone else's shoes and self-awareness to cover your tracks, and this would potentially be difficult for someone on the spectrum.
Sorry this is all over the place, I've been on vacation without my log-in and have 47 pages worth of reactions/thoughts.