Why Cecily says that she would never forgive Mr Worthing?

When Mr Worthing comes back to the country and discovers that Algernon is in his house, he is angry with him. Because Algy isn't allow to be with his dear ward Cecily, that is why the two men don't shake hands. But Cecily wants them to have a good relationship, so she says to Worthing that she would never forgive him if he doesn't shake hands with Algy. Can it be?