Over the decades and several road trips, Tully and Kate strengthen their bond and forge new relationships while occasionally testing them.

A teen magazine. A political investigation. A secret message. Shocking revelations lead to major questions for Sean, Tully and Kate.

As Tully's career takes off, uncomfortable encounters at work keep throwing her off track. Johnny's behavior causes concern among his loved ones.

From a double date in 1975 to Tully's search for her father in 2004, Tully and Kate attempt to take charge of their futures — but fate has other plans.

While celebrating their own freedom on Independence Day, Tully and Kate learn time and again that relying on each other may not be so bad after all.

Tully attempts to face unresolved loose ends from her past. But her choices lead to a potentially unforgivable mistake that impacts Kate's life.

Kate learns that dealing with an ex is always tricky, no matter the decade. After years of never saying sorry, Tully struggles with accountability.

For the first time in decades, Kate and Tully experience a year apart — but can they handle major life events without each other?

Kate has often felt invisible next to Tully through the years. But amid major changes, Kate realizes she may need her best friend by her side.

From bra-stuffing to breastfeeding, Kate experiences several bumps in the road on her journey from a self-conscious teen to a first-time mother.

Johnny and Kate reminisce at a party about a life-changing kiss in the same newsroom, 20 years earlier. Tully gives Danny advice on his love life.

A bridal shower stirs up resentments and memories, an awkward encounter leads to a life-changing question, and a tragedy shakes teenage Kate's world.

Kate and Johnny's loved ones gather for two very different celebrations. Tully gets tangled in a romantic dilemma, and Kate feels the weight of a secret.

Tully, Johnny and Marah try to find ways of coping after Kate's revelation. In the 1980s, Johnny wrestles with another piece of overwhelming news.

On a special day for the Mularkey family, Tully reflects on decades of work, love, grief and joy alongside her best friend. Kate faces the unknown.