@Tawana your looking at the glass half full, its 2 sides to what you are saying. Whereas you are looking at it like your man might want to have sex with her behind your back. The reason for doing it is so that he wont have to sneak and have sex behind your back. Because chances are he is already thinking about it.
A man will always be a man and the more open you are the more loyal and faithful he will be, even if he do find that other female to be more attractive.