I feel like the first thing I need to state is that open-relationships and polyamory are two different things. The former deals with sexual behavior while the latter is matters of intimacy, love, and partnership. Many (most?) poly families are closed and sex only occurs within the group of loving, consenting, adults.
While being in an open relationship is about freedom of sexual play the emphasis for me is on the freedom, not the sex. It is the freedom to be yourself, act as you wish without harming others, and enjoy the bond you may experience with another person. It is living your life without someone else putting restrictions on your behavior so that you aren’t concerned about identically behaving in a way that would cause the other person to be jealous (or worse, intentionally behaving that way and working to cover it up).
It really is much more about trust and communication than anything. Sex can be a fun and safe experience without emotional attachment. It can be an ego boost, an adrenaline rush, a surge of pleasure without making a big deal about it.On open relationship acknowledges that and also states that you trust the person to be honest about their attachment and communicate with you about what happens.
I’m not a one night stand type of person but it’s nice not to feel restrained if an opportunity and desire presents itself. Maybe I have too much of an emphasis on freedom, that is certainly possible, but the idea of preventing someone from doing something they enjoy because I might feel jealous (an internal emotion that only I can control) seems unfair. I practice open relationships because I want freedom and I want freedom for those I love. I don’t want any of my partners to feel doubt or question whether they should act based on what they think I might think. I want them to enjoy life to the fullest and I want to do the same.
Post Script: I realize that neither polyamory or open-relationships implies group sex as is implied in the picture, I just kind of liked the picture and thought it might catch an eye or two.