I want to make sure that I'm clear about this...I'm NOT saying that your H is having an affair ok? It's just been my experience that if he's not coming to you...he has a substitute of some type that fulfills that need. For my H it was his online sexual activity....for yours, it might be porn. Whatever it is...he's not turning that sexual energy towards you, but away from you where it's possible he feels safer.
My H had become programmed to honestly believe that women REALLY don't want sex, that he was on his own for it. Now it's very hard for him to change that behavior and believe I truly want that as part of our relationship. His programming kind of reinforced his whore/madonna complex...nice married women don't want it. yada, yada, yada.
My suggestion for installing a keylogger was really so that you can find out what he's doing....it IS very possible he looks at porn much more than you "think" he does. I was absolutely stunned when I saw how often my H looked online....and he was someone who if you had asked me previously I would have told you "would never do that, or wouldn't have time to do it."....he made the time, he took advantage of most of the times I was asleep and he wasn't....or I stepped out to run errands, or came home late from work....you name it.