There's a couple things to unpack here.
First, porn in itself isn't bad (there's this wave nowadays of demonizing it), but as everything else it can be harmful if it becomes an addiction or start to interfere with your life.
Second, the not enjoying part, you said you still enjoy 20% of the time, what is different about those times? Not everyone is compatible, everyone has had not stellar sex experiences. So is it a matter of expectation or lack of compatibility?
Lastly, if you believe porn is ultimately the culprit and you're addicted my advice would be seek professional help. You could try methods that people use to get out of addictions, if they work for you great, but if you can't professional help might be your best bet.