I must add a comment here, agreeing with some, challenging others.
The man who indulges in the inappropriate sights on the internet is NOT cheating on his wife. He is seeking some additional thrills to satisfy a taavah. His behavior has NOTHING to do with his wife, not her behavior towards him, not her nagging, not her appearance, nor their marital life together. However, the wife who discovers her husband with any such interests will understandably feel that he was cheating on her. But that does NOT put the onus of work on the wife. Rather, it is the sole responsibility of the husband to address his problem, the needed behavior change, and the character work to change him internally so that these taavos do not rule over him. Wife needs the guidance to support her husband through the work he needs to do to reclaim his status as the spiritual head of household.
Besides rare exceptions, the Rov has little to contribute to this. Most Rabbonim will either side with the husband, making light of the issue, prescribing a shiur of Chofetz Chaim or something otherwise holy but missing the point completely. Others will side with the wife, suggesting prisha, ultimatums, etc. That is why it is obvious to many that Rabbonim do not have much of a role in addressing marital issues, and certainly not most issues in the realm of mental health. In marital dilemmas, playing the role of the impartial is critical in bring about resolution of the problem. Doing so is the product of training, which the average Rov does not have.