Is it normal to be attracted by skinny girls?

Hi there, I have a strange fetish... I weight over 200lbs and my wife weights 90lbs... I really enjoy the way it feels having sex with her, the way she grabs my belly with her skinny hands, her tight body, her bony ass... I also asked her to call me "my big boy" and every time I ear her sweet voice calling me "my big boy", I get so excited! I feel like the fatter I get and the skinnier she gets, the happier I get... IIN?