When two hearts become one
In the end, they discovered that the longer that couples had been together, the more likely they were to have their heart rates sync on a daily basis. In other words, if one member of the household had an increase in heart rate, the other would soon follow and vice versa. These changes would continue whenever they were together throughout the day… More here.
I suspect that this is more related to empathy between two people who know and love each other more over time, but it is a nice thought to think that this can happen.