So non-monogamy is generally looked down upon because a lot of people have bad outcomes from it.

In the vast majority of these situations, the couple has decided to see other people because they are trying to avoid or alleviate the problems they are currently dealing with. If you or your spouse are not mature enough to handle one relationship, there’s no way in hell that the exponential complexity of a polyamorous relationship will work.

That being said, it sounds like you ARE one of the few people who are considering non-monogamy for the right reasons. Some of the most important things you need to do to make this successful:

• Great communication. No games, no bottling up your feelings. You need to be able to clearly express what your hopes and fears are, and then listen to those from each other person.
• Handle jealousy and loneliness. If you’re a jealous-type person, best to stop now. You need to be comfortable with your partners spending a significant amount of time together, without you. And you need to use that time doing things you want to do, not feeling left out.
• Secure in your self. Don’t base your self-worth on what your partner thinks about you. Successful non-monogamous people are not dependent on their partners as their sole source of happiness.
• Flexibility. You need to be adaptable to new situations, because a lot of things will be changing rapidly. Successful polyamorous people embrace the ever-changing nature of life rather than try to stop it.
• Be able to handle loss. All relationships end at some point. With non-monogamy, that happens far more often than with just two people. Remember that a relationship ending doesn’t invalidate the goodness it brought to your life in the past. You need to be prepared to process events like this.

One great book on non-monogamy is More Than Two. I highly recommend everybody giving it a read before moving forward.

Having a polyamorous relationship can be very fulfilling! If you can navigate the complexity, it’s a wonderful way to maximize life.