You may think the sign of an adult relationship is saying 'I love you', or knowing when to say sorry when you've messed up.
Nope. Apparently the true sign you're in a grown-up relationship is whether you know one another's Netflix passwords.
And particularly if you own one joint Netflix account.
Psychotherapist Barbara Neitlich, LCSW, told Mic: "Once, where you would share a key to your home, you now share your password to your Netflix account.
"Although at first glance it may not appear to be intimate, it is. Sharing your password to your Netflix account is like sharing a part of yourself: your likes, your dislikes, your recent viewing history.
"All of this allows your partner to get to know you better and feel closer to you."
Sharing a digital account can be viewed as an exploratory gesture, and a way for couples to start exploring their boundaries.
Dating coach Lori Salkin even said that sharing accounts "can be a great way to test how much you trust one another and your feelings about the relationship".
So if you trust your SO's unnervingly unhealthy interest in Making a Murderer, you may as well be saying an extra "I love you".
Feature image: Netflix