I discussed this with a sexual psychologist once. She was of the opinion that many men in partiuclar are almost addicted to the rush of orgasm (hormones mainly leading to this state of mind). That release alone is what they seek and so use porn to do so because visual stimuli is necessary for most men (which she regarded as pathetic, amongst other things )
Sex with another human is a different thing, you hit the nail on the head a couple of posts ago. This is the whole, loving, fulfilling experience, which porn isn't, it is just a means to an end.
He may have used porn as a quick fix to meet his physical/hormonal need for release and if your views on porn are very strong it's understandable that you find this difficult to deal with.
If porn were removed from the equation, would you feel entirely comfortable with him masturbating alone to meet his needs? If so then do try to remove it from the equation.
The brief objectification to attain gratification has absolutely no reflection on how he views you or intimate moments between you, the woman he loves. Because of his hormonal and psychological make up he may well find it difficult to grasp your perspective too.
Whereas men generally sustain a reasonable libido, regardless of ups and downs of life, women's libido can trail off and reduce to nothing according to emotional or physical turbulance, yet the more sex women have, the more they tend to need to remain generally satisfied (as opposed to gagging for it ).
Freya, we as women have the upper hand in the area of sex and satisfaction! We tend to have the capacity for imagination which means we don't have to place ourselves in what some would consider a questionable moral position (i.e. use of porn) to meet our needs unless we choose to.
Our libido's tend to respect the state of our life at any given point, while men have little choice but to meet their body's demands regardless.
I hope you both succeed in working through this together.