You may ask: Where does love figure in this equation? Shouldn't it be the decisive factor? Technically, yes, but in reality it can never be so pure. So, I would not judge Sandy for ending the relationship with Jay. It is in her right. But that's not saying she did not commit errors. Actually she tried to use one blunder to justify another.
First, she should not have agreed to go back to his hometown. In Chinese tradition, the decision to meet his parents for that particular occasion almost amounted to an engagement. It's not written but it's implicit.
She should have asked herself a string of tough questions before embarking on that trip: What if I don't like his parents or other family members? What if I hate his place of birth? What if I'm not accustomed to the weather, food, lodging etc? She should have gone only if the answer was: "It doesn't matter because I love him".
Once there, she should have known the propriety of being a guest, let alone a potential daughter-in-law. Generally his folks would have put in their best to make her happy. To expect them to serve her with a Shanghai standard fare is unrealistic. Unless they tried to gag her or do other immoral things to her, it would be extremely uncivilized to act the way she did.
I have been to some of the most poverty-stricken areas of the country and, to be fair, living standards even in those parts have risen substantially over the past few decades. Of course you can argue the rich-poor gap is wider now that the wealthiest have reached the stratosphere of high life. Beyond a certain level of basic living, a standard of decency should come into play. And I'm not including love, which is a luxury in this equation.