People who spend a lot of time together form something called transactive memory. Transactive memory is essentially where you begin to store memories in the person who you’re close to. It can be family or close friends, but most often it’s seen in couples.
For example, if one person in the relationship remembers, say, a password for a computer, the other might not bother to memorize it because they could ask their partner. The same might go for cooking. If one person knew how to cook, the other person in the relationship might not bother to learn because the other person could do it.
This is very convenient because one person can focus more on certain aspects of life, while the other can focus on other aspects of life (i.e. both people don’t really need to know how to hook up a TV. If one person can do it, then that’s sufficient). There is a problem, however, when couples break up.
Many couples feel like they’ve lost a part of themselves after they’ve broken up with their significant other. In some ways, they have. After a breakup, both people who were in the relationship can no longer call on the memories that they stored in the other person.
According to Harvard psychology professor Daniel Wegner:
Divorced people who suffer depression and complain of cognitive dysfunction may be expressing the loss of their external memory systems. They once were able to discuss their experiences to reach a shared understanding…. They once could count on access to a wide range of storage in their partner, and this, too, is gone…. The loss of transactive memory feels like losing a part of one’s own mind.
So that feeling of helplessness that people feel after losing their partner, it’s not unfounded. It isn’t just the emotional connection that they’ve lost; it is also literally a part of themselves that they no longer have.
It seems bizarre, but it’s something worth appreciating.