There are two types of infidelity- sexual and emotional. Sexually infidelity is less important than emotional infidelity. There are many shades of grey, and as a divorced woman I can tell you I would far rather find an escorts number in my ex husbands' phone than my best friend. I often wonder if the people who get on their high horse about this issue are somewhat shortsighted in the fact that marriage vows and friendship can be eternal- but sexual attraction can and does fade, many happy marriages are saved by the fact that there is a quick fix available.