WOW, what a post, lol.
Curiosity and Insecurity seem to be the two biggest things I pull out of your story. She's curious enough to go to see what it is about but too insecure to think about the possibilities beyond some voyeuristic fun.
Swinging is about trust and while the two of you may be deeply in love, the trust (in the context of swinging) has a long way to go still. You both are on the younger side of the scene and have plenty of time. Don't rush it.
Most people do not understand swinging and why people do it. Many never will and some will but still will not do it themselves. The ability to think of sex as something recreational is not easy and even those of us that can think of it that way still have our fair share of emotional stress on occasion.
Continue to work on your relationship, plant a seed now and let it grow. Not only did my wife eventually come to terms with swinging when I brought it up but she took the horse by the reigns and led the charge. It took two years for that to happen. Exercise patience and understanding and be thankful that she seems to have an open mind even though she isn't able to accept the idea of sharing yet.
There is no rush and if and when she comes to terms with the idea, and if she thinks she would like to try it, it won't be something you had to drag her into but something she made a conscious decision to do with you as a couple.