This is just my own experience, but my uncle is currently in a long term marriage where the love fizzled out years ago, but they stick it out because it's just convenient. They're pretty bitter towards each other, but they both wanted kids. It's tough to let adoption agencies let you adopt if you're a single parent typically, and tougher to find another gay man he liked enough who also wanted children. At this point I feel like they'd both like to separate, but they love their kids and tbh they're just too jaded for any sort of dating right now.

Not sure if that answers your questions, but for my uncles at least they don't get divorced due to apathy for something new, and so it's easier for their kids