Fiancé Masturbates at Work

Hi ladies, I'm in need of some advice. I'm 18 and my soon to be husband is 22. I found out he watches porn and masturbates at work. We are very sexually open and keep nothing(as far as I know) from each other. He told me a few months ago he watches porn on his phone almost everyday in the restroom at work. Sometimes he'll even masturbate after having sex with me, whether it be to porn, YouTube videos, or raunchy movies. Should I be concerned about him cheating because of his porn infatuation? I don't know how to help because we have sex at least every other day.