Noone can tell you if your SO looking at porn is cheating or not. We can't decide that for you. Every couple has to negotiate between themselves what is and is not considered infidelity. There are some women here who don't care at all if their husbands (bf's) look at porn - as long as they are not neglecting their lady's sexual needs. There are some women who say mags like Playboy are okay by them, but movies are not. It is often the case that men disagree about what constitutes cheating - and that is where the negotiation must come in and also the setting of boundaries. I personally set a boundary before I married my husband of zero porn tolerance. He agreed to that and understood my reasons for that boundary. He broke it and it took us a long time to recover after I found out, but we did, but it took alot of work on BOTH our parts to get back to a very good place in our marriage.
Your SO may tell you all men do it - not true. I know 100% for sure my husband has not looked at porn in well over a year - and HE is happier for the fact he hasn't. He feels good about himself and the fact he isn't lying to me. He is a total open book. I am too. I want to tell you right now that I made my own mistakes and bad choices in our marriage - and spent a great deal of time and energy addressing and correcting them. You'll see it said here often, and I have found it to be true, both parties have to be willing to give 100% to save and improve the relationship.
I doubt you are doing anything wrong. When your husband tells you he doesn't know why he does it - that may be embarassment at admitting his personal truth. I felt like you - that I was willing to do what he wanted in the bedroom and felt like you seem to - inadequate and inferior to the images he was using. I came to truly know that my husband simply used porn as a 'starter' for masturbation. I came to know he didn't masturbate because he preferred that to sex with me - only that once in a while, he would choose that as a quick, no pressure, stress free release. No pressure means they don't have to worry about also pleasing their lady. I know it sounds selfish, but once in a while I think that is okay (for me too btw). For my husband, from the time he was 12, masturbation included porn. So what we negotiated was that I have no problem at all if he chooses to masturbate, as long as no porn images are part of the process. We took many pics of me for him to utilize when he chooses that. I'm not saying that is a solution you can or should choose, but mention it as a compromise that worked out really well for us.
I read several pages of posts today and hope I remember your initial post correctly - you are the mom of 5, from 11 to 4 mos? I have 5 kiddos also, from 15 to 6. Don't blame your husband's looking at porn on the condition of your body or anything else you are doing. You have made it clear to him that it is hurtful to you right? And yet he persists? So - concrete suggestions to maybe help y'all. Don't throw your marriage away - you are right to want to fight for it. I have to admit my initial reaction was to just leave and take our kids away. I even threatened it - and I am not at all proud of that reaction, it was juvenile and full of resentment. Find a quiet time to talk to your husband. Tell him you want to talk about him looking at porn and how much it really hurts you. Let him know you are not being hysterical or overreacting - you are NOT the only woman who wishes to not have that in her marriage. Bring up what I said - ask him if he looks because it is a masturbation tool for him, and he is kind of embarrassed about wanting to masturbate sometimes. Don't be accusatory or angry - that will make him defensive and stop any possible good conversation y'all can have on the topic. Tell him you want to negotiate about the issue - find a boundary you can both be comfortable with. Stress the negotiate part. If porn is an absolute no for you - then ask him what you can do and how you can help him totally let go of it. If there is some level of porn you are comfortable with, tell him that. It may even be really good if in the first part of the conversation you tell him you are worried that your marriage is off track and ask him what he thinks you can do to help get it back on track. That will definitely defuse any defensiveness he may have. Listen with an open mind and be willling to address any issues he brings up. From there y'all can both negotiate to get what you want. I know all this sounds like you need an attorney over your shoulder giving you advice lol -but you really don't. All you really need is for both of you to be committed to repairing and improving this marriage.
You have my best wishes. I am sorry I wrote so much. If one or two sentences strike a chord and help you, then I'll be glad you read it. Welcome to the board and stay in touch and let us know how you are doing. Take care, Roxy