Early this morning, as my partner prepared to leave for work, some part of me thought it would be a good idea to engage her in an argument. Stump had woken up at 4:30, and so I’d been lying in bed for over an hour, trying to nurse him back to sleep, while simultaneously nursing my resentment over a comment my partner had made several days earlier. At 5:30, when Stump sat up and decided he was awake for good, I got up, found Kellie in the shower, opened my mouth, and released all of my venom. My period is due in two days.

I’m not normally like this, and therein lies the problem. Brooding comes naturally to me, but complaining doesn’t. All day long and into the night, every day and every night, I feel things and I think about them. I think about whether or not I should say them out loud. Usually, I choose not to.

Kellie is the opposite. She complains as she goes. She doesn’t brood. My emotions are a mystery to her—and by “mystery”, I don’t mean a puzzle that she longs to solve; I mean simply that she doesn’t know about them. I mean, she does in theory know that I have feelings, but if she’s not thinking about her own feelings, if she’s not constantly gauging every word she hears or says, assessing her own reactions, why would she be worried about mine?

Because of this, Kellie does not understand my PMS. She thinks it’s an annoyance that she has to put up with as part of the contract of being married to me. She does not see the benefit to me losing my cool—quite predictably—once a month.

Here’s an analogy. Some years ago, I took my dog Winston to a trainer because he was exhibiting aggressive behaviors, growling at kids as they ran by him, nipping at me if I tried to look at his hurt paw. The trainer introduced me to the concept of bite threshold.

All dogs, she said, are capable of biting another dog or human, but some dogs require far more to provoke them than others. The way she explained it, even Lassie could bite Timmy, but it would require the perfect combination of circumstances, say a thunderstorm at night and Timmy is wearing a mask and approaching Lassie while holding a large stick. But say you get a dog with an ultra-low threshold. It might just take a toddler waddling towards his food dish and he’s all up in her face.

So let’s say most days my bite threshold is relatively high. I’m no Lassie. I’m prone to growling in the evenings when I’m tired and the kids are tired and everyone’s resisting each other. But I also let a lot of stuff roll off my back.

On PMS days, my threshold suddenly drops. I’m like the sick dog in the above graphic. I might never like “getting my head touched” but on the average day, you’re never going to know that. But scratch me between the ears on a low threshold day and—SNAP! Now you know.

And here’s where the analogy breaks down. I realize that you don’t ever want your dog to snap, but in the case of your partner, you want her to say what’s on her mind sometimes, even if it comes out at 5:30 am when you are in the middle of enjoying your morning shower and expected the house to be quiet for the next forty-five minutes or so. You need her to explain to you, in no uncertain terms, the various reasons why she hates it when you scratch her head, and you do this All The Time. Come on. You want that. Don’t you?