Maseb
That’s interesting as conventional wisdom says we don’t have cycles like the girls do and I don’t really have any non-horny days. But, like you, I do get extra horny days. My best guess as to what is going on is that it is from pheromones, and those extra horny days are probably days when a girl we have been reasonably close to is in the most fertile part of her cycle.
This is a normal thing in animals, but while they can usually find the female concerned, our sense of smell seems to be to poor for that, but that doesn’t mean it is completely ineffective.