Plus 1?

Say you get invited to a wedding. You are given the option to bring someone: your invitation reads

Plus 1

If you’re not dating someone, can you bring your sibling? Your best friend?

Or does the Plus 1 really mean bring a date?

I hadn’t thought about this before, but I read somewhere about a Bride getting mad that her friend chose to bring a friend and not a significant other.

The bride said that the wedding meal is too expensive to be wasted on someone who really has no “meaning” to everyone.

The guest said that she did not want to sit at the singles table but wanted to have someone to talk to. She said no where in “plus 1” did it signify who that person was to be.

The bride said that it’s tradition to bring a date, not just anyone.

My understanding is that the bride and the guest are no longer friends.

So- what do you think plus 1 means?

Are the bride and the guest equally right (or wrong)? Or is there a clear winner to this argument.