Dear Mr. Smith,

 I have worked in the Sales Development as a salesman for one years, and I have been satisfied with this position very much. I appreciate your kind attention and care.

However, my boy friend and I have strong challenging intention to start our own business in a few years. At this time, this is a period for us to learn and accumulate relevant knowledge, I have decided to accept a post from a relative who offer me a good opportunity to practice and develop capability. I therefore write this notice to terminate my engagement with you. I am going to plan to end my job on next Monday, do you think workable?

Please let me know your opinion, thanks

Sincerely,

Smile