There's always a possibility that a person can get attracted to another. It's human nature, it's not wrong. But the reason why you're in a commitment is for you to discipline yourself. One may get attracted to numerous prospects and it's ok as long as you don't nurse the feeling and won't do something about it. The borderline between cheating and faithfulness is to recognize the reality that you already have the person that can give you more than what you can get from the cheap thrills of attraction.