maybe try to do a 50 percent water change and raise the temp a few degrees? I know this works with many fish and as JD's are ridiculously hardy, it can't hurt...
Could you or anyone post a picture of a female with her egg tube out? I obviously don't know what it looks like on my female because I thought I have saw it multiple times but apparently not.
Could they not be a pair anymore? I have never heard of that I thought they paired for life..