You hate/are afraid of boating, but know he loves the water and has put a lot of effort into planning this event.
What do you do?
At Kelleher International we are constantly urging our clients to be "open and honest" about everything. The more games, the less success. Before engaging your man in the discussion, think hard about possible ways you could make it work...could you pick up a Prada life jacket that would be funny to wear the whole trip, but also put you at ease on the water...could you pick up one of those pressure bracelets to fight your sea sickness... what fun and creative way can you solve your challenges with the sea?
Then, honestly and straghtforwardly engage your man. If you simply can't go out on the water, tell him. Let him know you tried to think of 10 different ways to make it happen, but you just can't. Don't promise "YES" if it fills you with dread. If you're open to an open sea voyage, share your fears and get him to help you think of ways to make-it-work. He might suggest you transform your plans, or come up with a winning solution like "tying in" like you were a crew member and physically attach you to the mast.
This will be the first of many things you do as a couple that is out of the each others' comfort zone - honest, head on discussion will make them all a non-event.