Open or Closed?

So a friend and I were talking a few minutes ago and it really got me thinking about how much do we actually know about our partners/significant others/ persons of interest. I mean if one is in a committed relationship and what not, shouldnt you know your partner in and out? Through and through... But looking at the people I know, no one is excluded from this, it seems as if some only show their partners one side of them. The side that they want to see, its like they do not fully know the person they married or are dating. But yet as I've observed those that are in open relationships they seem to be a lot more happy. I know many of ya'll are like open relationships? I dont wan't my partner having sex with other people. It's not really about having relations with other people. As someone I was talking to yesterday said that its the person being greedy and it's not that. It's being fully able to trust your partner, you know each others boundaries, you know them in and out there are no secrets between the two of you. If you two decide that you want to keep your sex life interesting and sleep with different people from time to time whose to say you can't do that. You're not cheating and most likely there are rules and limits to what you can and can not do. I don't see anything wrong with keeping your relationship fresh, you two don't set into a boring routine. If more people would educate themselves on open relationships and just stop being so closed minded then there would be far less cheating, lying, and not trusting your partner going on. I guess the way I was raised , the people I surround myself with, or just things that I've seen and learned taught me not to be so closed minded to certain things. I have more of an open mind than a lot of people. I tend to wanna see the positive side of things rather than be so negative. We only have one life, so let's not waste it being predictable and the you're left looking back wishing that you would've tried this or that.