I think I said this already, but in case I didn't. I think that she was branching out. I think she was finding herself again. I think this trip was, on some level, about being simply Sarai. Even her IG name, clever as it is, can be seen as indicative of this. I think she has been someone's daughter, then someone's wife and now someone's mother. I think she may have longed, for at least a few weeks, to simply be herself, undefined by her relationship to others. Mid-thirties, children relatively independent, going back to school, taking a photography class and falling in love with a new art form, all of these things can be signs of someone redefining themselves. Add that to the psychological effect that Sandy could have had (yes, I know her neighborhood was fine, but SI was annihilated in general, I'm sure there's a lot of people who suffered little or no physical damage, but spent time reassessing priorities.)
Please note: I am not saying in any way that she resents her parents, her husband or her children. Just that she was looking to figure out who she is.