Lots of men do this for various reasons which could be:
- They don't want to "bother" you for sex.
- They want a little variety.
- They are too nervous to talk to you about their fantasies so they use porn to fill the gap.
- They want to explore something new but think you won't like it or will demonize them for it. Men start their sexual peak about age 13 and they start that phase by constantly being demonized, mostly by girls and the demonization continues through their teens and twenties, year after year after year. How would you feel if someone did that to you? This leaves life long scars in some men.
None of this has anything to do with him loving you less or being committed to you less. The big problem here is 1) you have deep insecurities about him watching porn. I'll bet he knew you would react this way and that's why he hid it from you. As long as the porn is moderate, then it should not be a problem. Porn becomes a problem when it totally replaces his sex life and the other partner is unhappy.
I told him it made me feel inadequate, hurt and offended.
No one has control over your emotions but you, so stop blaming him for your own insecurities and ignorance about male sexuality. Some men complain when their women use a vibrator. It's just a tool and does not replace the man, and the same goes for porn. It's time to educate yourself about moderate porn use.
And yes, some men have such a high sex drive they HAVE to fap at work otherwise they can't think. (I've been there, it was pretty awkward.)
I have a long time interest in psychology, specializing in relationship dynamics for 30 years.
(Please note, we give the best advice we can based on the information given in a post. For better advice, please include the age of all romantic partners.)