Historically speaking, women weren't welcomed if they traveled alone. And, the mail-order bride was often a way for a woman to get WEst, at least get away from someplace she didn't want to be.
Perhaps an educated, foreward-thinking, independent woman of twenty or so would think to make her own mark in the West. It would be seen as an escape and a new place where old standards might not apply, where someone with the right spark could be a person and not be defined by whom she married? And, if she was "orphaned" and left with an inheritance that she couldn't control, having a husband she might be able to control might be appealing. I'm thinking her parents, a doctor father and her mother assisting him, died in the Influenza epidemic, leaving her educated and well-off, but still a young woman. So, her inheritance would be managed by a man, of course. And, that man might see her as "his" and this would make her want to run...fast and far.
Wagon trains didn't accept solitary females. The wives, believe it or don't, would make life a living hell for a single woman because they were a disruptive influence. Sad to say, generally speaking, my sex is often mean to its own to this day in the neverending contest for the choice male.
In her head, the man would be "old" and easily led.
But, in fact, following your storyline, they'd both be naive and somewhat stupid (AKA "innocent") to the true ways of the world.
What do you think. Oh, and I'm a freak about research and have costumed for this time period so I find it quite interesting. Feel free to PM. Just noticed your request for a PM on the first topic and see that I blew it off by the time I got to the last topic--sorry. The story was whirling and I lost my head a bit.