Honeymoon Late November. Is South Korea + Southeast Asia feasible?

Hi! I am starting the exciting yet slightly stressful task of planning our honeymoon. My fiancé was stationed in South Korea before I met him. I have always wanted to take a trip there together and thought our honeymoon would be the perfect time. My fiancé loves beach vacations though. It sounds like South Korea will be colder in late November, so I was hoping we could do half our honeymoon there and the second half at a tropical resort. Do you think this would be feasible/realistic/fun? What country or Island would be the easiest to get to from Korea? The plan is for our honeymoon to be about 2 weeks.

I would love any and all suggestions. I really appreciate the help. I love the reddit community!