Webcam Nonsense

One day I was looking at my SO's credit card statement just to see where we are paying it down. I noticed a lot of transactions with an odd name so I looked it up. It was to a porn site. He spent $400 in one month on it. I confronted him & he admitted he was watching girls on webcam. I'm not that type of person to watch porn so I'm confused & hurt. I feel like porn is one thing but to pay a lot of money to watch girls on webcam is straight up cheating! Thoughts...