At the end of the fifth season, Barry and Lainey announced their engagement after their prom, much to the disappointment of Barry’s mom, Beverly (Wendi McLendon-Covey). In the Season 6 premiere, Lainey promised that she’d give Beverly a lot of grandchildren, which helped her future mother-in-law cope with the news that her eldest son was getting married.
As the season progressed, however, the couple came to the realization that neither was ready for marriage.
By the middle of Season 6, Lainey had left to go to L.A. to pursue a singing career. While this was a convenient reason for her character to exit the series, the real reason for A.J. Michalka’s departure was because she got her own Goldbergs spin-off, Schooled.
Schooled made its debut in 2019, and it centers on Lainey’s life as a music teacher at her former high school. But, unlike The Goldbergs, the spin-off series takes place in the ’90s.
Source : https://www.distractify.com/p/what-happened-to-lainey-on-the-goldbergs