The more I hear, the more this trip seems odd to me. Any one factor can be easily explained, but the combination becomes harder to ignore.
Theres nothing strange about a married mother taking a trip abroad with a friend. However, this isnt just a married woman, it is a woman who has been married for over a decade to a man shes known since high school and has never been abroad. Never. No honeymoon in Jamaica, or week in Cancun, or trip to the Bahamas, all vacations that would be more usual and fairly easy to take without the kids. Wouldnt a first time traveler want to wait for a time that she and her husband could go as a couple, given that this isnt the kind of trip that is likely to be repeated at any time in the near future? If you are going to go without your family, why stay for 3 weeks? Wouldnt a ten day trip be plenty of time to explore some local culture, take some pictures, and go home? In fact, the whole idea of using photography as a key motivation for the trip strikes me as odd. She isnt a professional photographer, shes a hobbyist, and there are lots of beautiful places to take photos a lot closer to home.
Then theres the question of why Istanbul. It is supposed to be lovely, and it is a fairly popular destination for Americans (tied for 24 on the US Commerce Departments list) but still, it isnt London, Paris or Rome. Not the likeliest trip for a first-time traveler. Even if we assume she was able to get a better deal to Istanbul than to a place like Rome, I find it hard to believe she couldnt have taken a two week trip to a different city (and perhaps one more conveniently positioned for multi-country travel) for similar cost.
The side-trips add in another layer. Amsterdam is a popular city, but she only spent a day there despite, it seems, having free lodgings. Munich is not a hot-spot for tourists compared to a lot of other cities in the region. Even if we assume she met an IG friend and stayed for free there as well, that would hardly seem to warrant going to Munich rather than, say, staying in a hostel in Prague for two nights, which wouldnt break the bank either. Though there are satisfying explanations for why she might have gone from Istanbul to Amsterdam to Munich and back, rather than stopping in those cities on the way home, taken with everything else, it is another aspect of the trip that requires some explanation. As for the Amsterdam trip, how many women traveling alone especially married woman, even naïve ones would be comfortable couchsurfing with a man theyd never met in person before? Whether or not the guy had any really evil intentions, wouldnt you be worried about sending the wrong message?
The friend cancelling is the final bizarre piece of the puzzle for me. If she had cancelled because of an illness of death in the family, that would be one thing, but when you have a major trip planned, dont you make sure you can afford it well in advance of leaving? If she found she couldnt, couldnt she have cut the very long trip short instead of cancelling entirely? Or was there some other reason that she felt uncomfortable about this trip and backed out?
Look, normally I go by Occams razor: the simplest explanation is generally the right one. When a young girl goes missing after a night of partying in Aruba, Im not going to start entertaining the possibility of her being a drug mule or a CIA agent or any other wild explanation. But when this much doesnt add up, it gives you pause. It sound to me like Sarai Sierra wanted to come home. Whether she was involved in something less innocuous than photography while away is, to me, still a real question.