They’re not married, though. She may still be legally married to the husband she had last year ... some guy from a band?
It would be interesting to know whether non-marital-breakup stats correlate with divorce-initiation stats. A possible hypothesis is that a woman may file for divorce after the husband has moved on, because the woman has children and wants legal and financial issues nailed down. That wouldn’t apply in a non-marital situation.
My belief is the ratio is higher than 4:1 on the dating side of things.