Re: Is it human nature to be with the same person for so long?
Just being around awhile really wises one up...from observation to personal experience.
I suspect you are slowly letting out the more negative things (like your sister) now because you WANT someone to say what you're feeling.
Regarding p 0 r n: A guy said, "p 0 r n is great; it doesn't alter your day. You just take it out, do your business, and then put it back on the shelf when you're done". I think many guys come to treat women like that also...or maybe they're attracted to p 0 r n BECAUSE they're incapable of true intimacy. Chicken or the egg?
Regarding your son...it's possible that your husband will make his disappointment known if son doesn't want to farm. A good parent encourages his child to be himself, not force him to be like Daddy - that attitude is about Daddy, not the son. Men like this often make their children feel inadequate, sometimes even if son WANTS to follow in Daddy's footsteps, his work is never good enough for Daddy. You might have to work twice as hard to keep son's self-esteem up.
Good luck. It might take another big event to convince you to leave, but don't let the years waste away, only to find yourself too old and too financially tied to him to leave.