While Missy isn't intellectually gifted as her twin, she excels in other aspects of life. Multiple times in Young Sheldon, she has proven herself to be the best Cooper family member. She is funny, charming, street-smart, and social. So it's quite frustrating for fans that CBS tends to either cast her aside or totally ignore her. Young Sheldon season 6 takes these criticisms and baked it into Missy's arc as she starts acting out after feeling overlooked by her parents. Somehow, however, it seems like fate made her pay for her rebellious phase with her fate in The Big Bang Theory.
As the whole Cooper family dealt with the fallout from Georgie and Mandy's unexpected pregnancy, each member coped with things differently. However, while everyone was busy minding their own issues, Missy was the only one who offered support to all of them. So it's understandable that she is pissed in Young Sheldon season 6, particularly at her parents. She become so fed up with their continued ignorance that she dialed up her rebellious acts. Not only does she attempt to leave Medford and go to Florida via her and Paige's daring road trip, but she also complains about her town being boring with nothing else to do.
Despite desperately wanting to leave Medford, Texas, it was revealed in The Big Bang Theory that she never got the chance to move out. The nerd-centric sitcom didn't say where exactly Missy lived as an adult, but the fact that she and Mary had to fly together for Amy and Sheldon's wedding suggested that she was based near her mother. Somehow, this makes things worse for the only Cooper daughter knowing her tumultuous relationship with Mary. Sheldon was able to move far from their hometown, and at least Georgie never seemed like he wanted out of state.
When Missy appeared for the last time in The Big Bang Theory, she was pregnant with her second kid but was in the middle of separating from her husband. The CBS sitcom didn't get a chance to reveal more about how her marital woes panned out, but Jim Parsons' adult Sheldon narration in Young Sheldon was able to offer an update. As it turns out, Missy eventually found happiness in her personal life, getting re-married to an unnamed man and having more kids. No word, however, on what happened to her professional life, however.