Right now you are in a good position to ask for a threesome. Sounds heartless I know but its true.
Well, if Jon isn't really interested in preserving the marriage, at least this could be a fun diversion for a while, but she's likely to suggest the "other man" join them....Yuck!
I actually think some of curiouscynic's thoughts have merit (tho extreme). She probably is approaching 30 and in a "crisis" about where she is and where her life is going. I take it she is not preoccupied with raising children, which is usually the main emphasis a woman her age has. Then the crisis doesn't erupt until the kiddos are out of house as marrieds or off to college (no good JW situation of course), etc. I don't agree with the Swingers' Club suggestion. This is just too far out for most folks, let alone a JW who is still tied to the religion, and it would make Jon look like the Devil Incarnate. But demonstrating that there are new things yet to experience in your lives together is on track. It sounds like school & work have been on the front burners (all good goals), but she is questioning perhaps where her life is going. There are probably emotions torn between the new ramped up JW diatribes about "inactives" and her love in the marriage. Some see enjoying their relationship with a "worldly" or "fader" as a conflict with their loyalty to Jah.
COUNSELING is still the 1st step (despite CC's bad experience--many more commented on it favorably). Start off saying "we are here to SAVE our marriage, so the suggest to get a divorce is NOT an option, nor is the suggestion to "widen" our horizons with "other people". IF she won't go WITH you.....GO ALONE and hope that she will join you, although usually it is the alpha male who "doesn't need counseling". I think her full disclosure is a cry for help. Otherwise, she would have just kept it a secret or packed her bags and left.
Good luck in whatever choice you make. It is your life and your future and only you can decide and you will have to accept the consequences. If you take a chance and try to make it work, you can always change your mind later. If you pack up now, it's not likely you can "fix" it later.
DOC