Is he on any medications or had any changes concerning that. Sex does die down with time and he could be way more stressed out than you know. I would suggest toning it down a bit, and not trying to seduce him as frequently since that is just backfiring and obviously not working. Have you asked him if he has been masturbating or is interested in someone else? If he's masturbating a lot, ask him to try to not do that for a week. If he's easily able to get stimulation from himself it can make it harder to with other methods. If he's interested in someone else, than that should really be addressed in therapy I think. Honestly, it sounds to me like he could be struggling with severe self esteem issues. I'm guessing when he was younger he thought that he'd be more fit at this age, and own his own home, and have children and a higher income. If you believed you were ugly and worthless and unlovable, it probably wouldn't matter what he did, you still wouldn't believe it, at least not without working through these issues within yourself and possibly through therapy. Is he in therapy of any kind? Sometimes people need an unbiased mediater to bounce thoughts and ideas off of. I encourage you to not give up on this marriage though. It may take a lot of work, but you can get through this.