I realise no thought in and of itself is inherently sinful. I realise masturbation is a sin, all the time, and pornography or using anything to sexually stimulate oneself outside of the marriage bed is sinful, all the time.
But within the context of marriage, is it sinful for a man to indulge in his sexual fetishes, if the woman agrees to it? Let’s say a couple role-play as Mario and Princess Peach before they go to bed. Or they don a couple of fur suits and pretend they are furries/anthropomorphs. Or let’s say one of them likes gigantic breasts, and the other likes to be handcuffed to the bed. Or whatever strange things cross the minds of two sexual beings.
At what point does a fetish cross the line from being an act of love within marriage to being an act against love? Would it be ill-advised, for example, to marry someone who has gigantic breasts if you have a fetish for just such a thin? Would it be a good idea for such a man to seek out a flat-chested woman instead?
In short, when do fetishes work with God? Can they? Or do they work against His Will in the marriage bed?