As gas stations have enough room for more expensive “ultimate” versions of fuel, I don’t think that’s the reason. You can frequently get two kinds of Diesel and three kinds of Gas at the pump.
O. t. o. h…maybe the whole “premium fuel” hype resulted from stations having additional tanks after leaded fuel was phased out.
I can’t relate as well, as I live in a city where things are really really aafe. But there are places where a women are afraid to walk alone in the dark, even for a few steps. (And even in safe places some people are quite afraid)
I’d be very careful with remote diagnosis. You. might be right, she needs therapy. She might just be afraid, because something bad happened to her some time.
The only way is for OP to have a good talk with her what’s bothering her - and then he may come to a conclusion. As of now, there’s just not enough information.