Having several sexual experiences is something that each person should try at least once. The idea is to have pleasant sensations like you never imagined; or maybe you have imagined, but never acted on the fantasies. And the fact that you already have a stable partner doesn’t have to limit you in this regard.
Experimenting sexually can be quite an adventure. Each person gets to choose what they want to try and with who. Sometimes having a single partner for a long time can become a little stale and boring. That’s why people look for new experiences and sometimes decide to have fun with others.