How long is too long in a long distance relationship?

My boyfriend and I started dating in November of 2009. In April of 2010 he moved to China to teach English. 4 months ago I moved to Shanghai to study business and chinese, and since being here I have seen him once a month. However, he has just informed me that he is probably going to sign a contract for another year here in China, I leave in two weeks to return to the United States. During the coming year, he will be home for the month of September, he will try to come home during the Chinese New Year, and is in a wedding in May. So during this coming year, I will see him 2-3 times. After that year, I plan on returning to China to teach English myself, but am not sure if he will be staying for a 3rd year or not. So, I guess my question is, our relationship has already been successful long distance, but is 3 years pushing it?