What can be done when a partner shows more interest in watching a film about sex then they are in having sex with you? Often the knee jerk reaction is to blame the porn. People tend to treat it like a person that their partner is cheating with. Tempers can flare because the competition is a sexy tight body that can seemingly go forever and never get tired or have a single awkward moment.
On top of that he or she rewinds and has tons of friends that have no problem with group sex. In most normal cases if your partner going for a world record with the size of his or herporn download they are venting desires and fantasies that they feel they can not express with you. When the porn gets attacked they might feel justified in there judgement of the situation. Thinking that not only can they not bring up their fantasies they are not aloud to even watch them on film. There is the rare case of the person who just decides that fantasy is better then reality and that person more likely would rather watch porn then do anything including take care of themselves. when it comes to a other wise available partner who all the sudden takes a higher interest in x-films it is just time listen to them. The things that they might say could be hard to hear but at least growing closer again and getting sexy is possible.
With the second case it is no different then any addiction that takes over someones life. Intervene and push your partner to get help and join a group. If this is done in a shaming way with judgement there will likely be no change. If it is an addiction it is not about the relationship at all so do not take it personally and remember that the person is in pain. It can be hard to have compassion when feeling abandoned and compassion what works best for all involved.