My dear chap, you simply have to work out a compromise. As you probably have discovered night riding in woodland is AWESOME! It is a 'no brainer' you HAVE to find a solution. Lying is out. Need to know is in, so work out and agree to protocols she is happy with, ie spare lights, etc and phone. I like the Google thingy mentioned above as she has the option that she can reassure herself, which I think is the issue here. Discuss openly what it is she is worried about but neither reassure nor compound her at this point, wait until she has it off her chest. I am assuming yo have done this already?
There are some hazards, as have been pointed out, before one proceeds they must be gone over.
Animals in the woods, they dont know what to make of you, as well as stoned pot heads and "doggers", all of minor concern however. Me, personally I have encountered these as well as deer leaping up over the trail in front of me (a vertical height of of 3 metres I jest not!), shots fired at me(hey missed Ha! Ha!) and zombies. Zombies tend to be only of concern at twilight and if you stop. So dont. Right then. Lets sort this out for you chap.
Women are beautiful creatures and need to be nurtured to get the best out of them. If you have been married for so long then you must have a whole array of examples and arguments to use in your defence, show her the passion you have for riding and maybe she just might fall in love with the passionate man you have become and let you ride! This works for me and I still get to make love to my dirty little 17" hardass in the dark as well as have a beer and tea waiting for me when I get back! Oh yes you can't beat the little woman at home (no its illegal these days you know) but by jingo you can thrash the little madam hard and bounce her forks up and down up and down over and over. What fun you shall have touching her gears tenderly, the thrill as she lifts you out bthe saddle but hold on tight! Hmm, yes push your feet firmly into the pedals, or cleats if that sort of thing is your bag, and feel the rush as you flow ever on to finish. On the ride home, when cosy together for the last few minutes, remember to assure her and complement her on her lovely virtues. Tell her how she is going to be rewarded, because the girl deserves a reward!Lovely wax finish or somehing when daylight comes. Do be careful though, if in the moment of climactic joy you promise some sexy little fox forks with the latest kashima coating, and all you could ever afford is some wet lube for next time, then you are heading for trouble my man! She deserves better treatment and may run off with some local "chav" type who will only use her for wheelies. All the best old chap. Ride wild, Ride Free!