If they had just had SOMETHING indicating Ben Solo in the last scene, we could have read Rey’s adoption of the name as a reflection of her marriage into the family as an adult, but NO, Terrio didn’t want that, he wanted his Luke/Leia incest ship at the end, no uncomfortable reminders of flawed, “problematic” Skywalkers such as Anakin and Ben, so now the scene reads as two siblings adopting a grown-ass woman. Rey isn’t even a cuckoo that “takes” the name, she still has to be a little girl and look over to them for permission.
I 100% agree @corseque Rey was to enter the family as an adult woman marrying into it. TLJ sets that up, the dyad sets that up. As I posted yesterday, one of the few scenes in TROS in which Rey has agency are her scenes with Ben, such as when she kisses him. But that’s because its a continuation of her storyline from TLJ, in which she chooses to be with Ben, a decision she truly makes on her own. THAT is an entry into a family as an adult. It does not require the permission of Luke and Leia, only Ben (who of course accepts without question).
I hate this ending so much for how it infantilizes Rey, even in a moment in which she is supposed to be displaying agency, she lacks it altogether. She is framed as a little girl, no grief on her face at all because she doesn’t even get to be a widow here–that would make her an adult, and it seems Abrams and Terrio can’t have that.
