Luckily, being a species of intelligence (or supposedly so), Homo sapiens tends to have the gift of foresight, and particularly in more developed regions, easy access to reasonable education. In our culture, particularly in recent years, women have become more independent - they are free to work, free to be childless if they so wish, or free to have to children. There are generally no culture restraints here which forces women into a life of only marriage and breeding, staying at home and raising children, because they aren't allowed to work and earn their own living - in many places that is still very much the case - THOSE are the mothers who can complain about not coping, they generally have had no say in the matter.
There was no need to get to three, if you can't cope. Absolutely none. When choosing to have children, it shouldn't be done on a whim, and many questions are considered - one of those would be 'Can I even cope with another? Am I coping now? What if for whatever reason, I had to do this on my own? Could I cope?'.
I, as have many others, have seen the mothers not coping with one or two, the kids are unruly, uncontrollable, and for some reason, chooses to have another. Maybe lacking in the IQ department but again, not a a reasonable excuse IMO.
Sorry, the excuses aren't good enough. People who choose to have children, and have the freedom to choose not to, should do so responsibly. Having them running riot so they are a danger to themselves and others, (and as someone upthread pointed out, sharp objects everywhere and candles at the altar, IS dangerous!) because you cannot cope with the amount you spawned, is not responsible. That makes you a shit person as well as a shit parent.
Poor kids. Poor bystanders in the vicinity. No one likes people like this, and I daresay there are a great many of us who absolutely detest seeing people overbreed who really shouldn't be. It's grim.
There are a great many parents who manage this number and MORE, absolutely well and with class.