Is porn considered cheating?

Maddy
Whenever I'm snap chatting my boyfriend or when we are talking dirty to eachother over the phone, it doesn't really do anything for me. So I always feel bad watching porn or something while it's happening. However, I know I would feel worse if I didn't orgasm while he was talking dirty. I know it makes him feel better when I orgasm, but he doesn't know that I'm watching porn while it's happening. Is watching poem considered cheating?