Leave my job as PA probably returning to job after I come back from my trip to Greece.

After graduation I was looking for a job. After two months my best friend she found for me a job as a Personal Assistant. My boss ( an writer who works at home) during the interview told me that he was looking for someone for a long term but I told him that I didn't have any plans so I can take the job. . My boss saw in me that I was a little unsure because (thinking to myself) I had things that I wanted to do such as taking a CELTA couse which is a month intensive course to teach English not to mention that I will be going to Europe in the November. Because of my immigration situation, I cannot leave the country so I took a job as PA so I can earn money.
He told me to go and talk to my friend and she persuaded me to take the job until November and then quit. To make me feel better, she told me that every person who took the job as a PA left the job after 3-4 months.
November is fast approaching and I need to make up an excuse to leave this job. I must take this trip not for vacationing but for personal reasons.
Although it pays well, I am not happy with the job that I do, it doesn't challenge me enough not to mention that I have to work on HOLIDAYS which make me so mad!!
Upon the completion of this trip, I don't mind returning to this job (if he is going to ask to) or if I won't have that job anymore because I have better thing to do than replying to 120 emails and file things all that. This job doesn't have my future career at all.
I am not asking you to give me an excuse but the best way to approach this situation as I know that I am doing my job so well and I know that he sees it yet I would like a raccomendation letter from him ( if I ever need one).
Thanks
Emma

Honesty is the best policy... and being polite about it will help get that letter of recommendation.

Simply choose a good time to talk and explain that while you appreciate (and like) the job, some personal issues are pulling you away. That will open the door for you to ask for a letter of recommendation and mention that you'd like to come back someday if he'd have you.

Don't ever make excuses... just be honest. It may be hard at first, but you will become a better person and be better looked upon for it.

By the way, any intelligent person can see right through an excuse... whether you think you are getting away with it or not.