Studies show just seeing someone who’s freaking out can flood your body with the stress hormone, cortisol. And if your partner’s the one who’s stressed out, you’re 25% more likely to be affected than a stranger would be. The response is a holdover from our ancient ancestors…… Because if one person flipped out when a lion charged the village, everyone experienced the same fight-or-flight response, so the group could instantly go into defensive mode. Today, our reaction remains the same, but the “danger” is more likely to be a crashed computer.