Bluebird, I hope you don't think I meant to imply that you aren't submitting to your husband. You sound like a wonderful lady and are probably a wonderful wife.

Men are drawn to porn because their lives lack excitement and the thrill of the challenge. It is just an opinion, but it seems to me men are born with the hunter, protector, provider gene. When they get up go to work, come home, go bowling or fishing, hang out with the guys, go to church....after a while all that becomes unchallenging to them. They have nothing to prove to themselves or to anyone else. The praise ends and for many, their purpose for being alive ends when they retire.
The young sexy female who portrays herself as "innocent" just too hot for her own good, just needing a big hero like (one of the unwitting husbands) becomes a challenge. They imagine themselves in the conquest of the nubile female and winning the prize.
I also think that is what is wrong with our teens, the challenge, the prize to attain is either out of reach or not there at all. A reason to be, a challenge to show the world and their family that they are special and worthwhile. Mormons, which I do not believe in, but at least they do this right, send their young people out for a year to prove themselves. In Israel, the young are required to spend a year in the military.
Men need praise, they need a challenge, submission with a challenge. I don't have the answers, but I can assure you, I keep my husband on his toes all the time. I'm not that easy to "get". I challenge his ideas in a respectful way, I prod him to try new things, new places, different positions, new clothing, new vacation spots, I change my look frequently, my hair color on whim, my interests change.
Even changing what side of the bed you sleep on can make a difference. Shake up his life a bit. Separation would certainly do it.
He can probably sense you don't really want to have sex with him as much as he would like. There are other ways to please your man too....But you have to have the desire to do it. You have to make up your mind if he is worth your effort and do you really want him as a life partner until the end.