Partners usually get hurt by secrecy and comparison, not by the existence of adult content in the abstract. If you agreed to stop and kept going, that is a trust problem. If sex has gone quiet because the screen is easier, that is a desire problem. Both are common search reasons behind “can porn ruin a relationship.”
If you are quitting for the relationship, the other person needs to see behaviour, not speeches. A visible streak, a blocked phone, and fewer late nights with a locked door are more convincing than “I’ll try harder.”