Yeah same here. Didn't get married until 5 years after meeting. Like you say, depends on many factors, variables in the relationship.I know too many examples of these things happening in real life (myself included) to say they are true.
As has been said, it might be true for her, it might not, might depend on the guy or a dozen other factors.
If someone started putting pressure on me to get married after 2 years, that would be a red flag for sure. Why would getting married be such a big issue that you're prepared to walk from someone you should be in love with and presumably enjoy being around? Happy to cut them out your life just because not married - seems odd to me.
Can understand a bit more if mid-late 30's and they wanted kids, but you were dragging your heals about things.