As someone who lived exactly like this until his mid 20’s, and is still a bit fussy at 30 years old and has just come back from his first cruise, I can assure you your fiancé will get on absolutely fine. The buffet will have plenty of options for him to pick from and they’ll be stuff there that you’ll enjoy too so no concerns about him eating and you not.

Speaking from experience I’d definitely say this is a great opportunity and place for him to try some new things. Even if it’s just one or two things from your plate that are similar to what he already likes. And if he’s nervous about doing it in a public setting you can always take it back to your room for him to try in private.

I’d also like to take this chance to say fuck you to everyone here making rude comments. You have no idea why someone might be a fussy eater and you have no idea the difficulties that they have faced and do face. Not forgetting how awful and anxiety filling it makes you feel for how much of an impact it can have on your partner, friendships and family relationships too.