The fake-drama is Sorata falling for the manipulation and not having one ounce of backbone to consider his own worth. He allegedly loves her and has always worn his ring, but here he is willing to throw it all away based on one bitter person's opinion. But then again, no, that is not the real fake drama, the real one is the author throwing a roadblock in the way of progress in the relationship and the story. Good old Japanese guilt and shame at things going too well and having to put a stop to it.
The entire series, Sorata's been steadfast in how he feels about Miyuki.
The entire series,
everyone around him has told him he's just chasing a one-sided crush, that she's too good for him, and that it's just his own delusion because they've known each other since they were kids.
And to Miyuki's part - she could settle all of the confusion and suspicion of everyone else, if she'd just speak up and say the truth. She even still has the ring, on a necklace that she wears under her uniform...but she doesn't reveal it, she doesn't affirm why she doesn't wear it to Sorata, and she deflects or shuts down every instance of his trying to be kind with "Kyoto Phrases" that Sorata misinterprets due to the Brother's meddling years before.
Sorata's not spineless; he's just dealing with years' worth of mixed signals or seeming ambivalence from his fiancee, who has made no effort to correct the record on their relationship with him. Sure, she's emotionally closed off and awkward with her feelings, but we see her constantly gush about him in her own head or get outrageously jealous if he gets close to another girl or woman (like his coworker), but for all of Sorata's directness, Miyuki blocks him off.
And now that he both knows she's still super attached to the memory of her grandfather, how their entire relationship is due to some agreement made by their grandfathers, and how much she misses Kyoto,
on top of the years of the lopsided dynamic of their engagement because of
her refusal to be honest with her feelings, Sorata's reached the end of his rope.
This isn't him "throwing it all away on one bitter person's opinion". It's been in-world years in the making, and this is the point where it all comes to a head, culminating in the request from the Brother during this trip to Miyuki's home. Sorata's been hopeful but worn down all this time, and it's now the dam is starting to break.
And I wouldn't even call this a narrative roadblock.
Something needs to get Miyuki to realize she can't keep this behavior up, and now that Sorata's at the point where he feels like enough is enough, she'll need to make a decision as to whether she'll let him walk away or not.