I read a series of chapter books about 6 years ago, I think it was a trilogy. It was set in a fictional place a long time ago (it's kind of a mid-evil setting, if I remember correctly). It was a fantasy book. The main character was a teenage girl and I think she ran away, but I'm not entirely sure on that particular point. She falls into the company of a man (and possibly his brother?), who are "savages" of sorts. She eventually marries one of them. She's constantly writing things down in journals. I seem to remember something like 'Tiger' or 'Star' in one of the titles.

The White Hart by Nancy Springer

Posted on Amazon, "A tale of love, honor and evil. Two lads meet in a land riddled with magic and the evil of a dishonest "king". The story has tinges of the magic of King Arthur - a lad looks within himself, with the help of his friend and a maiden, and finds power to fight evil. The characters are complete, and brings you into the story. You care what happens to each one. One of Springers' earlier works, it's not as polished as later works. The ending may not turn out as you thought, but it makes sense. This book ties in with later books (Silver Sun and Sable Moon), but you don't have to read it to understand the later stories. Regal and heartrending, absolutely worth a weekend to read." As well as, "This is the enchanting story of three people, whose lives were interwoven by love, friendship, and desire for the destruction of evil. Set at the ancient times, when magic, nature, mortals and immortals exist together. The place itself, the Isle, gives readers the feel of the story--magical, lovely, nurturing, healing, but also foreboding and wicked."

If this is the book you are looking for, I can understand your desire to find it and read it again! The same thing happened to me and when I remembered the title, I found a copy on eBay, but it now appears available on Amazon.

Hope this is the book you had in mind!