I live in england but my boyfriend lives in new york , he wants me to come an live with him , how would I ? ?

He has most of his family there an mine all in england . For work he is a investor in real estate an in the stock market so if I was able to stay I would work with him if I was able to stay , but I have been told I can only stay for 90 days unless we show some kind of commitment what im guessing the mean married he would be happy to do that but I think it is to soon to be thinking about it . What are my options ?