Some of us have a very irregular cycle and can't take hormones due to medical conditions

If only knew, but you don't so you have no right to judge us. Alot of different things can occur that aren't in our hands.

How lovely for you that you don't understand the tyranny of an irregular period. Also OP could have needed to go on a new pill recently which can mess things up a bit. The best thing to do is accept you can't plan for every contingency on your wedding day and just remember it's all about sharing your life with another person, that's going to get messy and unpleasant sometimes too but the main thing is you'll be in it together.

People often plan their weddings and honeymoons up to a year in advance. Even if OP has a regular cycle, it is impossible to predict your period that far ahead (usually there's still plus/minus 3 days of variation). And stress can mess up even the most regular periods.

I was amazed by the ignorance of your comment, but then I realized you're a young, single guy, which might explain why you don't know much about periods.

Stress can also really impact periods (as someone else mentioned). My friend has an extremely regular period, but she was so stressed when she got married that her period came a full 12 days early. Unfortunate, but these things do happen!

I'm pretty sure you mean, "when the red river flows, take the dirt road"

Or her hubby can use his staff to part the red sea :)

Thank god somebody said it.