I’ve been invited to several weddings over the past year, and I find it interesting that none of them have even offered a vegetarian option. I don’t know what is common etiquette to do in this situation. The way I see it you have a few options:
Choose the cheapest option on the menu - probably the chicken, and then just eat the sides
Call or email the couple and inquiry about the alternatives - seems to be too forward when they have invited all these people
Write it in - just make your own box and check it - VEGETARIAN for me please - I haven’t tried this option yet.
Ask the waiter - they usually come around and check with you before they bring it to double check they are serving the right person, when they do ask for the vegetarian option, I’ve done this several times and it has worked great.
Don’t go - you probably don’t like those meat eaters anyway right? Just kidding.
So a wedding and a vegetarian can co-exist, it is all about doing it the right way without offending the couple, although I doubt you would.
On a different note you’ll be meeting new people probably at this wedding, so be prepared for the famous discussion around, where do you get your protein from?