Marriage readiness is often confused with relationship duration.
"We have been together five years."
"We are both over 30."
"Everyone expects us to marry."
Those facts tell you something about timing. They do not tell you whether the marriage itself has been thought through.
Readiness is less about a magic age and more about whether two adults understand the life they are agreeing to build.
You know the person beyond the best version
You have seen each other under pressure.
Tired.
Disappointed.