Well I was in an over 2 year relationship. One time I realized he was watching porn during the week, and masturbating to it. We weren't having sex, and he wasn't trying to please me at all. I think, in a long relationship, especially marriage, the husband or significant other, will not be able to see that this takes away from marriage. Why masturbate if you have someone to make love to? If it is something shared, ok, a shared interest. But hiding and lying, to me, shows that he is not letting you in on that part of his life, and makes me wonder what he needs that for, when he has you. I wasn't really offended at finding my partner doing this, but it did make me wonder why I wasn't enough to please him, since I did everything he liked in bed. I questioned what was so interesting about that to him, and if he needs an image of another woman in his mind to get aroused. I also think that it should be openly discussed in counseling if this bothers you. I wish you the best.