Consider a mid30-something couple, one spouse's second marriage, 2 children from first marriage. Remarried, third child with new spouse, preschool still.
New spouse didn't land halfway decent paying job, full time, til mid20s, no benefits, just hours, hours began getting consistently cut back and cut back and cut back (pre-marriage), had to change jobs 2-3 times including stints at bigbox store, and Walmart, for a handful of years to try to regain hours and some semblance of benefits. He gets sick, lands in hospital, no insurance, tells them he has no money to cover a bunch of tests they want to run, they run the tests anyway, he gets the bill, can't pay, has to declare bankruptcy.
A little later, met future spouse, love of his life, got married, he's now covered under her health insurance, so is any child they have together. She works fulltime at exhausting lower-paying job but with benefits and pension, he just works full time decent job, no benefits. Within a year or 2 of marriage, they have child together. Stable marriage, 3 kids, no welfare, still apartment living, saving for first house, barely making ends meet while trying to save for bigger living space. Hers is a state pension, living in state capitol, they need the benefits her job provides. They worry about money every month for bills, still trying to save, have set goals and timelines. Still a ways away, meanwhile home prices going back up again, but pay is not. will they ever get to move out of an apartment? maybe. retire? Her pension, fortunately she just landed a higher paying job in her same office. still mid30s. And that's one of the better lower middle-class scenarios in this day and age for a young married couple.