perhaps they think they are unhappy with what they have and can find something else better, over the fence...or perhaps its the thrill of doing something forbidden that is the big pull...or maybe they meet someone that just sends their head spinning...any or all of those might be reasons...affairs aren't the answer tho...because you are being untrue to yourself, not just your significant other. Nothing worse than lying to youself, because you are the ONE person you have to answer to for the rest of your life.

Ohh.and left one reason out...because they can...some folks just have affairs, or one night stands, because they think it won't hurt and no one will find out...but..again..still counts.