This doesn't make that much sense. Doesn't Lillie actively dislike battling?
Hence the reason for her disappointment, as her request for a little private time with the densest manmade material in human history, got rejected in favor for a battle.
Everyone's out today so...There's no one at home...Forget that! Let's have a pokemon battle!!A Pokemon battle!! A Pokemon battle!!Ah...Lillie, was your house over here?Yes! It's this way.So if you feel like it...Would you like to come over...?Okay...