Or, you could simply accept that some of us are wired for monogamy, some polyamory, others aren't wired for long-term relationships.
All three of these can be signs of personality disorders, emotional issues, or personal experiences that are unresolved in regards to how it affects your 'wiring'. I know some very happy people who are in open relationships, I know some people who are very happy in closed ones. I do not know any very happy people who are either poly or afraid of long-term commitment.