A lot of guys turn to p 0 r n when they are no longer visually stimulated by their spouse. VERY often, this is due to the stereotypical "false advertising" that women do prior to nesting.
Also, grow your hair, do the crunches and paint your nails for yourself, dear, not for him. Self-confidence is the sexiest thing of all...who cares what he's doing. If he's into p 0 r n and it bugs you, dump him. If he eats all the bananas in the house and THAT's a dealbreaker, dump him.
A whole industry has been built on fixing wrong relationships, people, it shouldn't be this hard.