Whether or not we think porn is not cheating, some people do think it is, and they are free to hold this belief if they wish. It's not up to anyone else to define it for them. But it is up to the two in the relationship to work it out and BOTH be able to agree on boundaries in the relationship and if they can.

Is it occasional porn viewing or is it an addiction, that distinction is important as well. Like I said tho, people have different boundaries with this stuff, and that is their right as well. What is important is if you can both come to agreement or not, or meet in the middle somewhere, as long as you meet. And you are BOTH happy with what you decide. If it's the hiding it and telling her you are not, then that is a matter of trust, which is probably more harmful than the porn to her I would imagine.

Just have to talk to each other and try to work it out. If it's not just trust, you cannot force people to be ok with porn, or to not be ok with it either. But hopefully you can both try to find ways to accept each other.