Its a year or two after Something has caused the collapse of society, Small towns are on their own.
One side effect (or maybe the cause) is a psychosis affecting many people that when they are triggered, they go into a murderous rage and kill people. Shortly later they snap out of it and are back to normal and have no memory of what happened. Society had devolved to the point that when the psychotics are identified, [usually IDed cause they just killed or tried to kill someone], they are just executed because no one knows what may trigger them, or has the resources to care for them if they lock them up.
The Protagonist is the town Sheriff/Police Chief. His wife is one of these Psychotics. But he has learned her trigger is Sex. (After Sex, she gets up, cooks a meal, and when he sits down to eat, attacks him). Now when she attacks him, he just locks her into the pantry or basement. (I think when she snaps out of her rage she is capable of unlocking the door again and goes back to being a normal housewife) Fortunately he lives a ways outside of town so townspeople don't visit.
Unfortunately, although rare, there are occasionally travelers along the road. When someone stops at the house when the Sheriff is at work, his wife psychosis causes her to seduce, feed and then attack and kill the traveler. So the Sheriff has a mess to clean he when he gets home.
He now has like 10-12 Graves (and abandoned cars/motorcycles?) along the road, to 'warn' travellers that stopping might be a bad idea.
The Mayor/Town leaders who know of her condition, are pressuring the Sheriff to get rid of his wife and move into town so he can better protect them from the roving gangs. (But he cant bring her to town, and does not want to kill her so he always refuses) The problem is, there are reports of a very large gang attacking nearby towns and heading to the town and the Mayor is starting to get desperate.
I mostly remember the beginning of the book, and little of the rest.
Pretty sure the book opens with the scene of the Protagonist waking up in the morning after having sex that night before and carefully going to eat breakfast in the kitchen. He is nearly surprised when his wife attacks him before he has eaten. But manages to subdue her and lock her in the pantry. [during or after this event is when the reader is filled in on whats happening] (He is nearly surprised because normally she attacks as they finish eating and she gets up to wash the dishes at the sink behind him)
The other scene I recall The Protagonist is talking to (The Mayor?) who mentions he hears there is another Car/Motorcycle/Grave in front of his house. Isn't that like the 12th(13th,14th?) one now. The Protagonist says yes, but its no one from town, so quit bugging him about it. We've had this discussion before, I'm not killing her, and if you try to force it, I will quit. But the mayor knows the Protagonist is VERY capable, and has been whats been holding the town together so just drops it.
I 'think' if I remember correctly the wife, who has now gone through the psychotic episodes 40-50 times now, is starting to realize something is seriously wrong (either flashbacks, or "waking up" in the pantry to many times) and is asking her husband about it. Which gives him hope maybe it can be reversed or cured.
- Book was almost certainly a US mass market paperback.