Do you think porn is cheating?

Just wondering who thinks porn is cheating? Curious because a friend of my husband tells me about his friends gf broke up with him because he masterbated to porn.. We are wondering how is it cheating?? I know everyone is different but I'm totally fine with my husband watching it.. It's not everyday of course.. But when you are 30 weeks preggo I really don't feel like having sex.. And if I don't help him in other ways he will go and watch porn sometimes. It's not like he's going off finding another woman! I rather it be his own hands! Lol. I just want to know how other women feel about it so I give his friend some advice since I have no clue what she's feeling...