FYI: You really shouldn't be using photos of people on your website without a valid model release. The model is the person in the photo - not the bride who invited them.
You may, as is done in journalism approach a subject you just photographed, note their identity and request permission to use their image. This is better- however, due to the fact that alcohol is being served and it's a party where no one expects to be modelling for advertising - the consent is easily contestable should a privacy issue arise.
What's the worst privacy issue you could face?
You photograph a guy dancing romantically with his mistress at a wedding his wife isn't privy too - and when her attorney uses it to win her a big financial award in divorce - the husband turns around and sues you for not obtaining a model release.