I know of a relative who got into a similar relationship 40 years ago. The woman is a resident of a small town and the man of a nearby rural area. So, the gap was much smaller than that between Sandy and Jay, but that was in an age when the residence permit system was much more rigid. So, it was like inter-caste dating. Even though she loved him, there was a constant put-down and humiliation because of the class difference.
From the moment I could understand such things, there was never any equality to speak of. Every time members of his family, such as brothers and sisters, came to town for a visit, it would be a clash of life-styles, which would look ludicrous in retrospect since the townsfolk were not much farther from subsistence back then.
Throughout history, the Chinese have placed an inordinate emphasis on "households matching each other" in marriage. Sandy and Jay would be seen by most as ill-matched due to their disparity in economic status. Mind you, not their own earnings, but those of their parents.
Of course, the balance could be corrected if he is much richer or possesses movie-star looks or has climbed up the social ladder to a rung that her family would envy.
Chinese arts and literature are chock-full of stories of lovers conquering that divide, which to me proves the norm is otherwise. In Jay's case, a small uptick in the looks department is not enough to enable him to vault over the invisible but enormous chasm.