I read through your 2 postings and I don't know if I'm qualified to comment or give advice, but my 2 cents is that both people really have to have the intent of giving to the relationship to make it work, compromise on both ends, and the willingness to be generous toward your partner and want the best for them. My husband and I both tell each other regularly that we love, appreciate, and don't take each other for granted, and it's not just lip service. If your husband is not contributing, then he has himself to blame if you left him. It does sound like if he has changed that much in your years together, he could have some
Depression issues or a physical metabolic change that is affecting his psyche. I also think people in our age range, 40's, 50's really do have mid-life crises that are especially hard without a strong spiritual center.
I consider myself pretty lucky in the relationship department, and grateful that I don't have to deal with what a lot of women my age are dealing with in their relationships, particularly when they married young. I met my husband when I was 30 and he was 39, and we were together 10 years before getting married, lived together for 3, got married just last year. That was more time than I needed, but he needed it. We have no children, which definitely makes it easier. We were bona fide grown ups when we met (though I don't always feel that way - lol!), and had plenty of time to test the waters with each other before committing, so I had absolutely no qualms that he was the person I wanted to grow old with. We have a few common interests and common values, but in many ways we are very different, and we give each other space to pursue our different interests. We still do things together, though, and I make an effort to do things that interest him occasionally and vice versa. I don't feel the intensity of the early sexual passion anymore, well, on occasion, but that's partly my hormones changing and partly just how I know it is when you've been together awhile, but my feelings for him are so much deeper now that we've had the intimacy of living together. I really respect him, feel a friendship with him, and just feel like I want to nurture and take care of him. It feels like a strong soul bond, but I have to sort of be mindful not to let that slip away from me, it's easy to become distant when we are wrapped up in our own tasks and neglect to make an effort. We do things for each other, we have disagreements sometimes, he gets prickly and irritable occasionally (he says it's when he knows his liver is congested, actually), and I just stay out of his way when he's like that. When I'm PMS-ing pretty hard, I don't even like the smell of him, but I know it's temporary, and sure enough he's back on a pedestal within a week. Our first year together in our house was really rough, I think I might have bailed had we been renting, but even then with all the emotional drama, I knew deep down things would work out because we were destined for each other and the initial turmoil was all part of a teaching and a way for me to re-think my own paradigms and viewpoints. I sometimes catch myself thinking about how I will survive emotionally when he's gone - assuming he goes first, and I can't even imagine the emptiness and how much I will miss him. Like the heartbreak of parting with someone you love that much almost makes you want to wall yourself off so it will hurt less.
I have just rambled a lot about my own relationship, but do you have any of those sorts of feelings toward your husband? I would not have been able to handle the porn thing, I'm with you on that, and yet I'm to the point with my husband that if I catch him rubbernecking other women (rare), I don't mind because I know I can trust him, I feel well loved, and I know he's not comparing me. I will say that he's an unusually stand-up guy, very focused on his own spiritual development and pretty enlightened in general, so I lucked out. He's on a path, I guess, and that does affect how he handles day to day situations and relationships.
I don't have any actual advice for you, I just wanted to post an example of what I think is a loving, committed relationship as a comparison (which still has its ups and downs, of course), because personally it would be hard for me to stay in a relationship where I routinely felt like I was not having that soul connection with my partner or felt somehow out of place and unhappy with my life with him. I sometimes feel like I am not doing my life's work, and think about what direction I might have taken had I not met my husband, but any unhappiness I feel about my current situation, career choice, etc. really has nothing to do with him, even if I had the opportunity for something much more exciting, it wouldn't be worth it if I had to give him up to do it, and in many ways I know my overall well-being is better because I met him. Basically, the things I do to make up for what I'm "missing" by choosing this life are acceptable stand-ins. Like any limitations or compromises I've made to be with him are a good trade. Have you made a good trade, or are you coming up with the short end of the stick all the time? It seems like he has to be willing to contribute and do his part.
Good luck, I know it's a lot more complicated when children are involved.