What’s a “bad marriage?” I think there are some that are truly bad and should be dissolved. But I think in many cases (perhaps the majority), people are simply indulging their own selfishness and poor impulse control at the expense of their kids. Americans highly prioritize (to my eyes, as a foreigner, childish) notions of self actualization and individual happiness over duty to family. And then there’s the kids whose parents never got married, typically because the father is stuck in some sort of extended adolescence.
My siblings in law come from one of those middle/lower middle class primarily white towns you sometimes read about, where two-parent families have declined tremendously. The devastation to the kids is real. Comfortable finances dissolve into financial strain. Lack of stability affects kids’ performance in school. Boys, in particular, suffer growing up without fathers to keep them in line. (It wasn’t until I had boys of my own that I realized how differently they often relate to their mothers versus their fathers. And trust me, we’re not modeling traditional gender roles at my house—my wife’s a scary trial lawyer who pays our mortgage.)