I'm going to get shot here but, here goes. I'm male. Have been married. Have been in a relationship where I wanted more sex, and in one where I wanted less / had a low libido.
(side note, OF is just like porn hub, the OF part makes no difference, it's just porn)
So, watching porn, and having sex with your partner are not the same, in fact they are really really different. It is entirely possible that you have an appetite for one, but not the other, and that those appetites fluctuate up and down.
Porn is often not about the sexual act, having an orgasm, it's often about excitement and novelty in a controlled, contained situation. Porn is also lot less complicated than real people - to have sex with someone you need to both be in the right place at the right time, not be tired, all sorts of things
Also, porn is addictive, we don't admit that as much as we should. I have been subject to it, to the point where it's blocked on my home network (though of course I can turn tat block off so...)
If you are tired, stressed, exhausted, worried at work/home/family - then porn can scratch a very physical itch, in a small amount of time, when you just can't face, reality, it's all got on top of you.
I am not doing your feelings down. they are real and valid and I don't blame you for feeling as you do. But, as a man, who see's himself in this story you drew, it's not anywhere near as open and shut as you think - aka he has time to wank but not time to sleep with you, thats really not it at all.
This is not cheating, that looks very different.
As always, I think a full and frank, but also fair and not initially blaming conversation would be best, maybe in front of a councillor who can help you navigate through this tricky time.