Yes, Galadriel knows Sauron, but their relationship evolved: she distrusted his disguised form (Annatar) during the forging of the Rings in Eregion, fled him through Moria, and later fought against his direct return, with her wisdom often clashing with his power, especially in The Rings of Power series, which portrays her as recognizing him earlier and more intensely than some book interpretations.
Why was Sauron afraid of Aragorn potentially possessing the Ring? Gandalf explains it in the Return of the King (during the council after the battle of the Pelennor fields) that Sauron would never think somebody would want to destroy the One Ring.
Sauron never loved Galadriel. He wanted to possess and use her for his own purposes.
Galadriel is still an elf at the end of the day, and Sauron is a Maia. Sauron is stronger than her. Eru is the in-universe equivalent to the biblical God and is the creator of everything. There is no comparison.
TL;DR: The writers deliberately depict Halbrand (Sauron in his fair form) as attempting to repent and return to the passions he had before he turned to evil. He fails, in part because of Galadriel's involvement.
It's not the years; it's the mileage. Gandalf isn't a Maia in the same way Sauron is. He was sent to middle earth as an old man, so his body is much more real than Sauron's “raiment”. He can't use his power to the same extent, he can't change his forms at will.
Instead, we have to consider that Sauron, the original owner, is not human, but has a quasi-divine status. Therefore ownership of the Ring is subject to Divine Law. With this precedent in mind, many of the ambiguities clear up nicely. After numerous transfers by violence and trickery, Frodo is the true owner.
Indeed, it seems Elrond used this The Rings of Power kiss not to admit his true feelings for Galadriel but so that he could slip her a pin from his cloak.
We know that Elrond, Elendil, Gil-Galad, Cìrdan, and Isildur were enough to beat Sauron (although he had been weakened by the fall of Nùmenor).
In their prime, Gandalf the White is more powerful than Galadriel. Gandalf, being a Maia spirit, belongs to a race of powerful divine beings called the Ainur, who existed before the world was even created.
Just like it had happened with their parents (also Half- Elves), they were given a choice to choose the life of an Elf or the life of a Human. Elrond chose the immortality of Elves, and his brother chose the Humans, the first one to do so. He lived 500 years, which is not too shabby.
In the Days before days, Sauron was corrupted by Melkor (later named Morgoth) to betray the Valar and serve him. He served as Morgoth's chief lieutenant throughout the First Age.
Elrond chose the fate of the Elves and therefore the choice was presented to his children. The reason why Eldarion and his sisters (the children of Aragorn and Arwen) were born mortal was because Arwen chose mortality and therefore that fate was passed on to the rest of their line.
As a Maia, Gandalf was an angelic being in human form, in service to the Creator (Eru Ilúvatar) and the Creator's 'Secret Fire'. He took on the specific form of an old man as a sign of his humility. His role was to advise but never to attempt to match Sauron's strength.
He did not trust Gollum, for he divined something indomitable in him, which could not be overcome, even by the Shadow of Fear, except by destroying him.
Legolas is introduced at the Council of Elrond in Rivendell, where he came as a messenger from his father to discuss Gollum's escape from their guard.
It tells you why right in the book, Sauron releases him because he knows Gollum will go after the ring, and can be watched, leading Sauron to the ring.
Glorfindel was among the mightiest Elves, and once the lord of the house of the Golden Flower in Gondolin. After a valiant death in the First Age, he was re-embodied by the Valar and returned to Middle-earth millennia afterward.
The Ring's effects
Inversely, the hobbits' good-naturedness and lack of ambition makes them less susceptible to the Ring's promises of power, as in Frodo and Samwise Gamgee, who are able to handle the Ring for extended periods of time.
By lingering behind, she chose mortality so she could rejoin him. She died a year after him of heartbreak if I recall correctly. She chose a mortal life to be with Aragorn, as such she could no longer travel to or set foot upon Valinor. Gimli, Bilbo, Frodo, and Sam were the only mortals ever granted passage to Valinor.
Though its people were diminished, Rivendell was maintained, for a while, by Elladan and Elrohir. They were later joined by Celeborn, who left East Lórien within a few years of Galadriel's departure with Elrond's party. It is not known when Rivendell was finally abandoned, but shortly before he died in F.A.
One of the effects of the ring is that it takes you to the unseen world. That is why Frodo and Bilbo become invisible. Sauron exists in both worlds. Therefor the ring doesn't move him anywhere and he remains visible.
Except for Tom Bombadil, nobody seemed to be immune to the corrupting effects of the One Ring, even powerful beings like Gandalf and Galadriel, who refused to wield it out of the knowledge that they would become like Sauron himself.
Exclusive worldwide rights to motion picture, merchandising, stage and other rights in certain literary works of J. R. R. Tolkien including The Hobbit and The Lord of the Rings were sold by Tolkien himself to United Artists in 1969, reportedly for a small amount, and are currently owned by Middle-earth Enterprises ( ...