The crazy thing about it, is that I'm the oldest. My grandmother forced my parents to stop seeing each other by my first birthday and arranged for my mom to marry her best friend's son instead of my dad. Their marriage was 31 years overdue. Even my step dad and his new girlfriend were for it. My mom had started emotionally distancing herself from my step dad and was thinking about divorce when I was 10 when she accidentally got pregnant with my sister on our family vacation. She decided to stay for my sister and brothers. I grew up w/o my dad with a step dad who was emotionally abusive and sometimes physically abusive, but my sister was too young to remember that. What she remembers is her dad spoiling her trying to buy her love and her getting to stay with mom while I went to college, got married, and started my own family.
And yes, both my parents and my step dad and his new girlfriend are much happier now. My sister unfriended my parents on facebook and her dad when he took my parent's side. But she still talks to them, relies on them to watch my niece when her and her boyfriend or my nieces biological father are working. She likes my dad, lived with him and my mom for 2 years before they decided to get married, but it was the name change that hurt her the most I think.