Rigid/ inflexible/ easily irritated partner

Does anyone here have a husband/boyfriend so fixed to plans/routine - even on vacation - that minor changes or delays got them into horrible moods, depleted of energy, needing to withdraw & not interact?

My partner is an introvert normally, but worse than ever with this lately. We’re on a much-needed overseas family trip and his moods are setting me on edge. I feel like I need to help keep him happy and calm but it’s giving me anxiety myself.

Any advice?