Open marriage / relationship ?

It surely isn't suitable for everyone, but I can think of many reasons for a monogamous relationship not working with some interests or circumstances. Then polyamory can make the difference between multiple people being unhappy alone or happy together. I don't know if it's for me and think communication is key, but I'm definitely not against it for others who are in agreement about it. Lying and cheating is no good, but open relationships can exist without that.