When you make room in your relationship to honor the possibility of outside attractions and the feelings they create, it can help you stay connected and engaged with each other instead of developing separate lives where you keep your attractions hidden. Being able to talk about scary topics like outside attractions can even help prevent affairs from happening.
There was a time when it was considered inappropriate to discuss sex and sexual anxieties. Certainly, what you got up to in the bedroom was nobody's business but your own. You would probably rather have all your teeth removed with no anaesthetic, than admit to a complete stranger that your sex life had dried up.