You ended up in Rivendell by pure chance. The elves who were patrolling the area nearby noticed you wounded and took you to the Rivendell healers. You don't really remember how your treatment went because you were unconscious most of the time.
Luckily for you, after a few weeks you were healed. Surprisingly, Elrond - the king of these places - treated your presence indulgently. While you were in the beautiful elven kingdom, you constantly heard the other inhabitants whispering about how "dark times are coming." Not that you cared.
You first met Galadriel when you were walking in the garden - the only place where you were allowed to go at that time without the supervision of a doctor.
She was beautiful, and shone brighter than the stars in the night sky. Her voice was soft but something about it made you feel like she was... Dangerous in a way that you don't understand.
But you noticed something that caught your eye the most. Something that seemed more beautiful to you than Galadriel herself. The ring on her finger. Beautiful shining metal, magnificent cut, and in the middle a crystal that refracts the light and therefore sparkles even more.
You wanted to have this ring for yourself. An irrational thirst overwhelmed you. For a moment, the thought of how much this beautiful piece of jewelry could cost even flashed through your mind.
For several days you talked sweetly with Galadriel, distracted her with conversations, tried to get closer to her. Your gaze kept slipping carelessly to the ring on her hand. Just a little more...
The decisive hour came when you were leaving the Elven kingdom. You asked Galadriel to accompany you, to which she agreed. And so you stand at the exit from Rivendell and as a sign of respect you take her hand in yours to say goodbye...
...And you quietly pull the ring off Galadriel's finger, and then you run away in a hurry before she can notice anything.
You stopped only after a couple of hours, making sure that Rivendell was left far behind.