There's been a lot of debate as to how Cassian throwing away his solstice gift to Nesta compares to Azriel giving away his solstice gift to Gwyn.
Elriels try to say that both actions are the same, in that the gift doesn't end up in the intended recipient's hand, but that doesn't change the romantic intent behind the giving of the gift, or symbolic weight of the gift. They say that Azriel gave away Elain's gift in the same sort of mindset Cassian threw away Nesta's, an act made in pain and a desire to be rid of the gift which represents thwarted love.
Gwynriels respond that a major difference is that whereas Cassian threw the gift in the Sidra, Azriel gave the gift to another woman. Cassian throwing the gift away meant no other woman could have it, it was Nesta's or no one's. Azriel however is able to transfer the gift to Gwyn, and takes great pleasure in thinking about her receiving it.
There's a certain emphasis on how well suited the gift is for Gwyn. Clotho talks about how Gwyn deserves such a beautiful gift, and Azriel thinks about how Gwyn's eyes will light up as she receives it, an image that creates a "spark" in his chest, which he tucks away, comparing the image of Gwyn receiving the gift to the necklace itself, a "secret thing of lovely beauty".
Cassian's gift for Nesta could only be for Nesta. Azriel's gift for Elain turned out to be remarkably suitable for Gwyn.
Elriels will argue that Cassian throwing the gift away, compared to Azriel giving the gift away, is more about each man's personality, than their feeligns for the giftee. Cassian is hot tempered and impulsive, whereas Azriel is more rational and (seemingly) cool tempered.
However, we see that Azriel rejects the "rational" choice, the choice he makes without emotion, or in cool practicality. He initially intends to return the gift, probably for a refund. That's the cool, methodical response to his gift being rejected. Instead he finds himself going to Clotho and asking the gift to be given to Gwyn, compelled by reasons he can't quite fathom. Giving Gwyn the gift was the emotional choice.
Some Elriel fans also cite Azriel saying to give the necklace to anyone to suggest that Azriel had no particular desire for Gwyn to have the gift, but in doing so they ignore the structuring of the passage. Azriel goes to Clotho, to the library, with the direct intent of giving the necklace to Gwyn. It's only as he and Clotho converse, and Azriel's motivations come under some mild scrutiny, that he almost backtracks and says "give it to anyone" (para). His thought process wasn't "ok well I'll just donate the gift to the priestesses, hey maybe Gwyn would like it". It was "I want to give Gwyn this necklace, my actions are being noted, ok I'll say just give it to anyone".
Far from indicating a lack of care on Azriel's part, it actually suggests a degree of vulnerability, something about Azriel giving Gwyn the necklace, and being seen to give Gwyn the necklace, makes him feel vulnerable and defensive.
There is also Cassian and Azriel's reactions to how they both dispose of their respective gifts. Cassian regrets throwing his gift away the minute he has done it. He wishes still for Nesta to have it, and he regrets his rash action in casting it into the river.
Azriel doesn't regret giving the gift to Gwyn. The thought of Gwyn receiving the gift pleases him, not only does he dwell on the thought of Gwyn receiving the gift with pleasure, it also gives him a sense of peace. It's something he dwells on as he drifts off to sleep, thinking about her smile and her eyes lighting up.
Cassian throws away Nesta's gift and regrets it. Azriel gives away Elain's gift and is pleased with it.