Your boyfriend’s sexual compulsion seems to operate like an addiction and he would do well to see a therapist. Perhaps the best way is to make an appointment with a couples counselor to discuss the issue. The couples counselor can make the recommendations for change after meeting you together. You have done the right thing by giving him another chance, but talking about it in couples therapy would be a good start. But ultimately some therapy for your boyfriend to understand how his compulsion operates would be important.