Some couples like (and yes women aswell) pornography. In my opinion men who can't find the pleasure from his wife search other fantasies within porns. (It's same for the women) Some couples watch porn together to learn new positions, new techniques. Some couples enjoy watching porn during sex. There are various reasons to watch/collect porn. Again in my opinion if a man likes having sex with his wife and also watches porn sometimes, it's not a big deal. If a woman doesn't like her husband's porn activites, instead of being sad or mumbling about the topic, she should talk to his husband and/or a psychologist. Porn industry is a huge one and it'll always be with us until the end.