Heck, I'll take a yuri version of LOTR any day !
I suppose the One Ring would extend her lifespan . . .
No, it would stretch it til every waking moment was a burden. She would become a wraith, a fate far worse than Death (Eru's Gift to Men).
Were this a tale in Middle Earth, is almost 100% a certainty to go badly for the Elf queen. Presumably she would not be one of the Eldar, but one of the Avari. Her blonde hair makes her one of the exceedingly rare ones in fact (and no, Legolas Greenleaf did NOT have blonde hair, Jackson completely f'ed that up). Almost no Elf outside of those with Minyar (aka Vanyar) blood had blonde hair. Assuming she were Avarin (ie - a Silvan Elf), she likely remained in Middle Earth after the last of the Quendi to depart sailed to Aman with Cirdan the Shipwright. And no, she doesn't get the 'I'm one of the Peredhil' excuses, cause any non-Melian derived Half-Elves all died as mortals: the children of Imrazôr the Numenorean (first Prince of Dol Amroth) and the Silvan Elf Mithrellas come immediately to mind.
Elves mate for life and only a handful of exceptions have ever been recorded. Fëanor's mother, Miriel, dying early being the first such instance of a husband deprived of his mate so early in his life that he was given dispensation to marry again as Miriel refused to be reembodied because of the drain birthing Fëanor.
Assuming she lived in grief, she might very well die from it. That presents a problem: Elves are immortal within the confines of Arda, unlike Men who die and pass to somewhere only Mandos and Manwë know. As in their spirit will remain in Arda until its end. When they die, which was never supposed to happen until Morgoth (ie - Satan) screwed things up, they are summoned to The Halls of Mandos. However, they can refuse such a summons, which leaves their spirits (called The Houseless) open to the corruption caused by Morgoth. The Barrow-Wights were inhabited by such spirits of Elves. The Dead Men of Dunharrow and The Nazgul (and those few Wraiths like them) are literally the only exceptions to the Doom of Men. Every other Undead in Middle Earth is either some fell spirit or an Elf who perished and refused The Summons.
There is a reason Elves and Men almost never pair-bonded in Tolkien's legendarium. Its not to say they didn't, but almost every last pairing (or potential pairing) ended in tragedy for someone (usually both lovers). And that is the tragedy of Tolkien's work.
[This has been your overly pedantic essay on how Elves and Men in Middle Earth make terrible couples]
