I watch porn all the time and love my girlfriend very much. I don't know you, so I don't know if he's satisfied with the relationship or not. But the fact the he watches porn in no way necessarily means that he does. It's not because you're not doing enough in bed. It's not because you're not doing it often enough either. It's not your fault at all. But it's not his fault either. Assuming this is a stable and happy relationship he is just looking at porn because it entertains him.
For me, I watch porn because I like the variety and it entertains me sexually. But I don't love those porn stars. In fact, the LAST thing I would want to do is have sex with a porn star. Call me crazy, but I don't like having sex with a revolving door. Yes, the better majority of guys do look at porn. Most women/girls are in denial about that, but they do.
As for the reason why he's doing it in secret: It could be because he knew you would get mad. Which is wrong on his part. But at the same time you can see where he's coming from.
The truth is, if he was with one of those girls in the video he would be on the internet looking at picture of you*. It has nothing to do with you as an individual or anything you did wrong. You didn't do anything wrong. Most of us are just hardwired to want to watch porn. It's a billion dollar industry. To us it doesn't seem wrong because we know that it doesn't take anything away from how we feel about our significant others. My girlfriend know I watch porn. At first she didn't like it. But now she doesn't care. We even watch porn together sometimes. But for the most part she thinks it's "gross".
Another way of looking at it: Do you read romance novels? Do you ever fantasize about other men? Do you like romantic movies? That's like porn for women. But it doesn't take anything away from your relationship with your husband does it?
* You know what I mean.

Comment