I watched an anime once about a girl with brown hair. She met a man in a forest that saved her from a strange life form. That man ends up being her soulmate from another time line. I believe they was reincarnations of gods? I think the man was tall with black hair? I also believe he had powers that relate to destruction or fire?
The story (from what I remember) is a girl waking up from hypersleep, she lived in our near future. She awakes in a far away future, where apocalypse came and nature took its rights back. She meets a boy that becomes her soulmate, and is capable of fusing with a nature spirit to save her. (I saw it a long time ago, sorry if it's not that exactly)
Have you looked for a anime movie called Mononoke? It is also about reincarnated gods in a forest. Even if it is not what you are looking for, it is a recommendation of mine. One of the best anime movies i've ever seen.