Early on in The Big Bang Theory Theory, Sheldon talked about the contentious relationship between his dad and mother, with most of the blame being on the Cooper patriarch. It didn't help that whenever Mary would visit and talk about her late husband, she always painted him in a negative light. Yet, in Young Sheldon, George Sr. is rarely the bad father that he was described as in TBBT. He likes drinking beer as his son recalled, and he has committed some questionable actions in the prequel series, but for the most part, he's been a devoted and loving father. As for his dynamic with Mary, they have gone through some rough patches and they tend to bicker, but there's no toxicity around them — at least not enough to hint at George having an affair and his impending divorce from Mary.
Understandably, Young Sheldon tweaked certain aspects of Sheldon's upbringing to better suit the tone of the show; this includes making George Sr. and Mary's relationship likable and relatable. The first few seasons of the show avoided major conflict between the parents — but as it slowly progresses forward in time, the prequel will have to sooner or later acknowledge a more tumultuous period of the Coopers' marriage. Young Sheldon has begun to reconcile these two different versions of George Sr. and Mary's dynamic by dropping hints in season 4. The episode "A Second Prodigy and The Hottest Tips For Pouty Lips," heavily hinted that there's something wrong with their marriage: that's why Mary became so paranoid after hearing about what went down between Brenda and Herschel. There hasn't been any major argument between the Coopers in the last little while — at least nothing shown on screen. But it's totally possible that the sitcom is simply not tackling those issues head-on, with their arguments potentially happening behind closed doors.
This idea was backed up by Young Sheldon's decision to skip the fallout of Mary's decision to spend $100 on fabrics for her renewed passion for sewing. Instead of showing the couple fully arguing, the sitcom immediately cut to George Sr. having a beer with his friend and complaining about what went down. During the conversation, it's clear that Mary wasn't happy with his initial outburst about her impulsive spending. This creative decision allows the series to still establish that Mary and George argued in Young Sheldon — without the sitcom getting bogged down by the conflicts. When the problems culminate in a massive argument that causes irreparable damage to the marriage, it won't feel like it came out of nowhere. Additionally, it also gives George Sr. the motivation to cheat — explaining the character beat without justifying it.
With three more seasons of Young Sheldon confirmed, the spin-off will have to eventually deal with the ugly side of George Sr. and Mary's relationship. Granted, the show's writers have admitted that they have no issues breaking The Big Bang Theory continuity for the sake of storytelling — but the show will at least need to acknowledge Sheldon's recollection of his parents' dynamic, as well as their inevitable split. Otherwise, it will be totally detrimental to his characterization in the original show, especially since the fighting subtly put such an emotional and psychological strain on him.