It's wrong not to attend parties you were invited to.
John has been invited to a baby shower but also has a report to finish for work.
John wants to decide how to allocate his time that evening.
John attends the baby shower and finishes his report when he gets home.
John stays home and finishes his work without telling the host he can't make it to the baby shower.
The party host is happy to see John and enjoys the baby shower.
The party host is sad that John never showed up to the party.