MARK is what you'd call a classic alpha male. He loved his family; his footy; his cars; his beer; his mates and he worked as a tradie. I was 20 when I met him at football club event. I was attracted to him from the outset. He had a charisma that drew people to him, and he was a funny bugger. However, soon after we started dating, I noticed something different about Mark.

We are in our early forties with three teenage kids and our year marriage is mostly happy. On the way home my wife asked if I wanted to give it a try. I rang my mate the next day and asked if we could join in a session with them. We went to their house the next weekend and after sharing a few bottles of wine we went to their bedroom. I was kissing his wife and then having sex with her but what I was really focused on was hearing my wife enjoying herself.

He met a new woman who made him feel alive again and his wife met a rich man who took her away on expensive travels around the world. For a marriage to stay alive, it usually needs to have an ongoing, mutually enjoyable storyline that it is aiming to unfold over time. For example: When a couple first gets married, the life story that they are aiming for is usually to get a house together, have children and enjoy the fun, responsibilities, love and challenges that come with maintaining close family relationships.

June 1, pm Updated June 1, pm. Not for so-called Stags, though. These guys get their rocks off watching their wife or girlfriend having sex with other dudes.