There are three potential issues here: 1) that your DH is discounting/ignoring/minimizing how his behaviors make you feel, and 2) how his porn habit affects your sex life, and 3) this could be an addiction. (I say this because my NXH had an addictive personality, and porn - the hardcore stuff - was one of his addictions. He simply could not/would not stop.)

Some questions to ask yourself:
#1 - Does your DH understand that when he pays lip service to your request, he's invalidating and being disrespectful of your feelings, and by extension, you?
#2 - Does DH favor watching porn over being intimate with you? (If the answer to this question is "no," then #1 is the bigger issue.)
#3 - Do you think DH could stop if he wanted to? Or does he just not want to?
#4 - How do you know he continues to look at online porn? (If you're checking up on his internet usage, this is a sign that, at a very deep level, you don't trust him. And he has proven himself untrustworthy.)

I went through something very similar with NXH. Most porn is very misogynistic and portrays women as objects to be used. (Note that I say *most:* there is some great feminist porn out there, but something tells me your DH is not watching this particular type.)

This is a very touchy subject for both men and women. If you don't feel comfortable enough to broach the subject with him, I would suggest employing a neutral third party (marriage counseling) to help you walk this emotional minefield. Don't make excuses and say yours is an "otherwise good" marriage; without trust and respect, there are some serious cracks in the foundation you've built together. Work to patch them now, before they spread and undermine things further.