I would say this is more akin to addiction. If he is getting action 4-5 times a week (nice work btw;p) and still has to look at porn that much, something is up I would think. Especially if he is lying about it. That's too bad that he is lying about this addiction and is putting it before you. I would put the marriage on hold until you get this issue solved. If he is lying to you about something as petty as this, what else is he hiding?
Here is a decent article I found:
Internet Porn: Worse Than Crack?