Are porn sites, online chatting and dating sites fun or cheating?

just curious, if its possible for a bf to be going on dating sites, porn sites, or chats, for "fun" and have it be completely loyal still.

i would never think so, and in my past it led me to find his path of cheating.but are their cases where its normal, and perfectly harmless.

i just feel like everyone needs some flirtation from a stranger once in a while to make them feel sexy. sometimse hearing it from your partner doesnt sound believable. but when you need to get intimacy with a stranger while you are dating someone, than you have a problem.