[sereneiders]

I am not sure if I am following you here.

If I am guessing right, I believe the answer is IDENTIFICATION with the people around you.

As for now, you trust each other and you're confident about what leads you to this world, how much you treasure your relationship, the limits you set, and how careful you want to be with yourselves and with other people (and, surely, how much you'd hate to lead others into the same sort of hurtful scenarios you'd like to avoid).

At some point you will realize that most other couples are in the very same page you are, they feel the same way about swinging, they treasure their relationships and they want to be as careful as you want to be. Even more, they started the same way you do, they had (and may still share) the same fears you two have, and they would hate to force a situation where someone's else drama may blow up in their bed.

Once that happens, you'd identify yourself with them, much like facing a mirror producing a reflection of yourselves, and you end up noticing that the interaction with those people (even if not involving sex) feeds your soul and feeds your relationship: you'd be sharing with them a tridimensional view of the human relationships that you'd find hard to share with anyone else outside this world.

You get confident, and eventually you give up some of your fears and test the waters with others... or you realize that you reached a limit and sharing what you already do is enough for both of you, and it would be fine for them as well.