It’s more likely that when she had his children, Elon felt like he had total control over her and could ramp up his abuse of her. This is a classic maneuver by abusive men. Marriage and moving in together also tend to cause them to lash out, but having a baby usually really does it for them because the woman is often physically weakened by it. This includes raping the woman after she gave birth and isn’t healed.

Once the abuse escalates, the woman is able to realize he wasn’t going to change and that he’d get worse. She is able to realize it’s too much. Someone like Grimes with money and power can escape more easily once they realize this.

So yeah it’s less to do with Grimes becoming a mother and realizing he wasn’t good enough (implying his behavior has been steady/the same), and more like him trapping her and taking off his mask.

Men like Elon - narcissistic and obsessed with women, especially trans women - have a compulsion to control women like dolls.