I have been researching for some time, but I have come across something that I don't understand

That doesn't mean to say that it is difficult as it's probably just me!

Having traced the marriage of a female with 2 first names I get "christian name * surname" and when I try to find who she was married to, I find that there are no other people registered on the same day, just her.
Can anyone tell me what this means?

Many thanks.