Only allow one person to freak out at a time
Nothing is more embarrassing than standing next to a partner who's berating a gate agent for a weather delay. Except two people irrationally berating a gate agent for a weather delay. Then you just look like a couple of maniacs who absolutely deserve each other.
Figure out who requires patience, and when
Your partner might be one of those people who needs to be told you're leaving an hour earlier than, well, you're actually leaving. But you may require an hour to get ready for dinner. You both have times you'll need the other to be patient with you, and once you establish those, everything else will run smoother.
Above all else, let the small stuff go
Just like in daily life, but even more so when you're away. You have to let the small shit go without comment or pouting. It's that simple -- just let it go.