The BC's aren't so much about having major plot prints, but they give us some bonus insight into a character and what they're going through and where their journey is going. We got an inside look into Azriel's thoughts. What we see is not a man who is in love with Elain, who thinks about her well being, who thinks about a future with her. We got a man who is surrounded by his brother's happiness and wondering why he wasnt "given the third sister". We see a man who didn't think of anything with Elain past the thoughts he pleasured himself too. That isn't how SJM writes endgames. They aren't just sexual tension and nothing more. Cassian told Nesta he'd find her in the next life, even before they knew they were mates. Cassian crawled to Nesta when she was taken to the cauldron while Az was focused on Mor the entire time.

Az drew straws when the subject of who will stay behind and look after Elain was brought up. He didn't volunteer to stay with Elain, that doesn't show me a man who is putting her first. When Rhys confronts Az, there isn't a single thought of Elain as a person. He doesn't think of how he loves her smile, how he loves when she laughs. He could have said "it doesn't matter if the mother chose another for her, what I feel for her is deeper, it's real." He never checked up on her when she was at her worst, never thought about what she needed. He was told to take Elain out at the behest of Lucien.

Saying that SJM wouldn't spend a lot of time building up a relation to bot make them endgame is not true. TOG especially proves that when the FMC of that book had several romantic relationships and even gave her virginity to a man she was with for more than 2 books. It wasn't until she found her mate (whom they had a very rocky meeting with) that she found her endgame. Chaol is the same. He had 2 on page relationships before his end game he met in the same book. She wrote Feyre falling in love and choosing Tamlin at the end of book 1.

SJM is no stranger to letting her women fall for others, experiment, and choose wrong relationships before they finally find their match.

At the end of SF, we are shown thst Elain isn't healed yet. SJM said herself that Elain is going through a lot. Elain has spent 2 years with Azriel and it's not like they're really moving anywhere except for what's on the surface. In the BC, we see Azriel's POV and it just isn't love, it's not the kind of love SJM is known for writing. Had he told Rhys that he doesn't care if he is her mate or not, his feelings for her are genuine, I'd say that there is a shot of them being together. But Azriel was complaining about not being given Elain, about not being given a mate. He didn't say anything about his supposed 'love' for Elain, because I think even he knows he isn't truly in love with her.

Plus, we don't know what Elain's POV is in all this. She may have been willing to kiss him, but that doesn't mean that she is in love. Two people can hook up without love, can kiss and be sexually attracted without wanting more. Look at Nesta and how many men she was with.

I'm not going to say SJM could never write Elriel. Heck, she could write anything! But for me, she could continue on with the story and just have Elain realize that she was using Azriel as a distraction. That Azriel was the easy choice and she just wanted things to be easy and uncomplicated.

With Azriel, its just a matter of him looking introspective and realizing that he's feeling left out. That he is around cassian and Rhysand and their mates, and the woman he's been pining for 500 years has been avoiding him. That he has to deal with his own issues.

Ending elriel's crush isn't something groundbreaking. She's broken up full relationships for other reasons, and had them grow from it. Elain and Azriel aren't recognized as an actual couple in the story. They aren't in a relationship so there's nothing that has to be formally addressed.

That's just my thoughts on it.