Why does a man flirt with other women?

Even when everything is fine in your relationship, tiny "cheating" will always be in the man's head! They invigorate, increase testosterone, internal energy and fortitude. Being a decent spouse, he brings this emotional “bouquet” to you in the form of gifts, passion and “purring” in your ear. And at this moment you love him even more or you think: “What has suddenly come over him?”. It does not matter how old the husband is - 20 or 60. He will always look at women appraisingly and flirt with them. This is nature! And he is a male. Another question: is it possible to reduce his "hunt" for women to a minimum?