If not living in Thailand, I guess the next best thing is someone who lives here and is a native Thai speaker..... does this have anything to do with that young lady? Asking her for lessons might just be the key to learning it, but to make any language as comfortable as your native tongue takes time and you must speak it constantly.
I tried to learn Spanish just because I wanted to learn a language. After going through and completing 3 levels of a course, I can speak it well enough to get myself into trouble ..... but not out.
I spent a few weeks in Argentina and got along fairly well on my own. I lived for a week with some folks who spoke no English and we had some simple conversations with the aid of a Spanish/English dictionary from time to time. I have no doubt that if I had the freedom to spend 6 months totally immersed in the country and the language, I would be able to get along well at the end of that time. The problem is, who today has the time and finances needed to do that? I guess one could always go there and apply for a job as an English teacher. I've heard of a number of folks doing that very thing. 2 folks I know are doing that right now.....both teaching English as a second language.....one in Chile and the other in China.