We tend to think that friendships are meant to be easy. That they don't require the work that a romantic relationship might need.

But our relationships with our closest friends can be just as intense as any other, and just as important to keep healthy.

Aminatou Sow and Ann Friedman are the hosts of the podcast Call Your Girlfriend. And when they felt that their friendship was drifting apart despite their best efforts, they decided to get outside help.

They've written about it in their new book, Big Friendship.