It's not the fault of the children, but it's definitely because they had children. Two partners (two marriages) who had red flags the size of Texas, I was jumping up and down raising the alarm, and they still decided 'let's have kids, it'll be great for our relationship' which quickly turned into one side realizing 'I can leave, sit on my ass, and collect child support while the dumbass works his hands to the bone'. And then he did it again with partner #2!

Ulterior motives and people being massive pieces of shit is the root cause, but putting their dick in crazy (twice) lit the fuse. Trying to be a good person ('you don't need to get an abortion, I can provide for us, I'll get a second job...') locked him into the scenario he's now dreading.