I am asked this question quite often, and even though the true answer is complex, the shortest version I could give in most situation is: because of a broken heart. I first came to spend 5 months on an old sailing boat in an Oregonian marina.
I know, it sounds strange, and there is more to it than that.
My first ever serious relationship in Europe crashed in a catastrophic for me manner. The curious thing about it was that I ended it before it exploded in my face, after my most serious attempt to keep it for the rest of my life.
I was still in love, but I stopped even liking this person. I was already living by myself in Düsseldorf when I received a call from his employee from another firm. She told me what he did while in relationship with me, and that she was not the only one.
First, I spent three days laying on the floor of my almost empty studio, crying or shouting in pain, but mostly without movement. Second, I went to check myself on HIV and everything else - I got lucky.
During that time I was accepted to a master's degree program in computer science, and was finishing the first semester despite separation difficulties.
The knowledge that my five-year love story was a lie felt like my soul was ripped out of my body. I knew I wanted to live, but I did not know how to exist, if it makes any sense. I needed to be physically far away. I tried to travel for a few days in Europe, but that was not it.
Then, a cool vegan friend had offered me to stay on his old second boat in Oregon, and I agreed. Thinking about the heavy Earth between me and everything what my life was, gave me a significant relief. I gave almost all of the rest of my things away, yet again, and flew to San Francisco.