Question: I'm a married man and I masturbate, fantasying some people I know or celebrities. Is it bad or is it okay?
Answer: Fantasies are a common phenomenon for most of the population on planet Earth. However, everyone's experience of this qualifying as infidelity varies and is subjective. If you feel comfortable sharing and communicating about this with your partner(s), that's great! If not, know that you have a sexual and sensual life that can be only yours and doesn't have to require your partner(s) presence or involvement.
That being said, fantasies are harmless as long as you don't commit a wrongful act or harm anyone in the process of pleasuring yourself. It is just another of your mind's way of saying "let's get experimental". If you feel guilty or shameful or confused about them, you could try communicating or exploring the acts with your partner(s) and maybe channelize the exploration energy for real. In the post below, I discuss some ways you can practice exploring your fantasies for some inspiration.