"Why Why Why" is a country-infused folk-pop song with introspective lyrics about a former relationship and Mendes' struggles with anxiety, which led him to cancel a concert tour in 2022.

Anthony Wilson and Connor Brashier directed the music video for "Why Why Why", which premiered on the same date as the single's release.

[12] Mendes performed "Why Why Why" and the entirety of Shawn at an intimate concert tour in the United States in 2024, marketed as "for friends and family only".

[13][14] It was included on Shawn Mendes: For Friends and Family Only (A Live Concert Film), which premiered on November 14, 2024.

[18] In its vulnerable lyrics,[19] Mendes expresses himself about his own mental health issues and struggles with anxiety that led him to cancel his tour,[17] as well as a previous relationship.

[20] A verse of the song about Mendes imaginating a potential future as a father and a "pregnancy scare" received media coverage.

[25] In a positive review, Isadora Wandermurem of Clash described the song as a "refreshing shift from the singer's previous productions, highlighting his willingness to explore new sounds".

[18] While adding "Why Why Why" to its list of the "must-hear" releases of the week, Billboard's Jason Lipshutz said that it is "highly compelling", and finds Mendes "vulnerable to the point of sounding haunted".