Jason's a very normal boyfriend. (Yeah right). He likes to be useful, to take care of people, and sometimes he's a little weird about it. But that's how he shows he cares, quiet acts of service, thoughtful actions that speak louder than words could.
That's why he tracks your cycle on his phone, to be prepared. Not that he'd need to, after being with you for a few years he knew the signs immediately. Which is why he knew it was approaching. He didn't need a phone to tell him the luteal phase was making an exit.
He noticed the way you'd rub your neck, or your forehead, the way you popped your wrists and stretched more often. The way your nose would twitch when you went into the kitchen looking for a snack only to find that the smells alone were gonna make you nauseous. He knew you didn't like to make a big deal about it, you knew the signs, knew what was happening. And he didn't think it was a big deal either, he's always been comfortable around menstruation. Because he's not a child who thinks they're gross, he's seen way worse.
But he also didn't like seeing you uncomfortable. He knew he couldn't do much. Other than rub your feet when you rested on the couch with them sprawled across his lap. Or massage your neck and shoulders to take some of the ache away. Make you tea and go out to stock up on pain killers.
So when he came back from an early, casual, evening briefing with the bats and saw you laying on your back on the couch with your headphones in, the TV on low volume, he knew more or less what it was about and made his way over, after taking off his shoes and jacket.
"Hey, you good?" he asked, keeping his voice soft, running his fingers up and down your arm as he stood next to the couch.