As aggravating as it seemed, Devile could not deny the fact that Zeba was telling the truth. They had just informed him that the ritual was going to take place that night and he was trying to go visit the princess. There was no need for him to deceive himself that his stay with the princess would be awesome. He wouldn't even concentrate while he is with her because he would be busy thinking about the evil thing that he was going to do that night.
What was worse is that the Princess was unaware of his real identity -- how would she react when she finds out that the title, 'second son of Satan' wasn't an ordinary title but a fact. Would she leave him after finding out that indeed he is the son of Lucifer? Goddamn it...