I am with you that watching porn at work (in the car?) seems bizarre -- but from my experience working in corporate IT, it's way more common than you'd think.

I would keep his porn habit completely separate from the main problem that he isn't demonstrating enough interest in you sexually. I think it's a problem that affects a lot/most long term relationships. I don't know how to fix it. Will he talk with you about it? Is he worried about having another child?