They are using each other .
Harry gave her game play away when she said in the DR (regarding Nick buying his immunity) that she was SO shocked and had Nick down as the winner of the series . So that reveals the reason why she latched onto him from the minute she entered the house .
Nick is a user . He has been using them all since day one . All this face touching, hair fluffing,poking, scratching, jiggling is all to depict himself as nervous and vulnerable .He most certainly is neither, he is sleekit and crafty as a fox playing the house pet in the same way Chloe has done . Both are acting .
Anyway this recent trouble is down to mummy dearest trilling how Nikki is coming to tea at Castle Nick ,which indicates her approval of the little gremlin .We all know Nikki hated Harry , so siding with Nikki in such a subtle way means Harry is unwelcome on the homestead .Lets face it Nick has no job and is therefore dependent on the parents , so their word will be law and mummy has spoken .