“Crazy Ex-girlfriend,” The CW’s unique musical sitcom, is back with its third season and another new theme song.  So far it’s diverging from its whimsical roots in favor of more overtly dark themes than previous seasons.

Despite having low viewership compared to other CW series, the show has found a cult following and critical success, winning a Critic’s Choice Award, a Golden Globe and two Primetime Emmys.

It follows Rebecca Bunch (Rachel Bloom), an eccentric New York City lawyer tired of her fast-paced life. She bumps into her ex-boyfriend, Josh Chan (Vincent Rodriguez III), and on a whim decides to follow him back to his hometown of West Covina in southern California. In the ensuing mayhem, Rebecca carves out a life for herself complete with friends and a new career.

Last season ended in a classic cliffhanger  — Josh leaves Rebecca at the altar — with a twist. He’s decided to join the priesthood.

Understandably devastated, Rebecca disappears after swearing revenge. The first episode of the current season centers around her declining inner-emotional state and her resultant failed attempts at avenging her broken heart.

From this and the following episode, one might assume this season is entirely focused on her need for retribution against Josh, making for a boring and typical storyline.

Fortunately, it has begun to steer away from this as a main concept and instead focuses on Rebecca’s mental health.

This is a risky choice for the show and doesn’t always work out. In some aspects, it may have taken this subject a little too far, and the series doesn’t always correctly portray the complexities of mental illness. However, it presents a much less superficial depiction than many other sitcoms who have attempted to explore the same theme.

In previous seasons, the series has danced around the question of whether the protagonist really is crazy with a capital “C.” In season three, this question is finally answered when Rebecca is diagnosed with Borderline Personality Disorder (BPD).

This revelation doesn’t just represent a missing piece to the puzzle. It is also a step in the right direction in terms of character development. Because Rebecca finally knows — and eventually accepts — the cause of all her past emotional trauma, she can now take steps toward possible recovery.

Her diagnosis also leaves room for some interesting reactions from her friends and family. Knowing she will never be cured in the traditional sense, her loved ones must now stand by her and accept who she is or confirm her fears of abandonment.

Though this season focuses on the darker sides of Rebecca’s character, it still has not lost “Crazy Ex-girlfriend’s” lighthearted charm. The song and dance numbers remain clever and hilarious while staying relevant to this season’s overall message.

This isn’t surprising as the show has past experience delving into controversial subjects with inoffensive humor and coming out on the other side unscathed. They’ve cracked jokes about the gender wage gap during a dream ghost dance sequence, and they’ve even addressed addiction through Josh’s best friend’s alcoholism.

With this season, “Crazy Ex-girlfriend” once again proves a triumph. In the beginning, it  seemed superficial and unoriginal. But as it progresses and continues to explore mental illness as a central theme, it’s becoming more entertaining and relatable. The show adds even more depth while remaining its same, charming self.