Of course, I don't wish to dismiss Ben's homesickness or how much he must have missed his parents, just that it's hardly the same as Finn being torn from his family and then being robbed of his very name and any link to what he was before.

Rey wants to belong to a family, she thinks she needs to be 'somebody' to wield the Force, whereas Kylo would like nothing more to be a 'nobody', hence him constantly using that against her because he secretly envies how free she is of any legacy.