Hello, I did the same and I can give the email of the person who have helped us to find a romantic place hotel, restaurant, beautifull photo spot and photographer etc... everything to have a unforgiven moment.
She's in Phuket but can organise in other islands more remote in the phang nga bay, Krabi and Kao lak.
if think you can send me a mail via my profile.
I wish you all the best...