The more subjective cases (too immature, had a psychological problem, couldn't balance a checkbook, didn't get along with the neighbors, what have you) wouldn't be an issue, because prior to V2, those weren't grounds for annulment.
Right.
I was taught the other major ground is deceit of an important nature before marriage. For instance, if one person had been married before, is an alcoholic and/or a drug addict, had a
history of physical abuse or mental illness, and kept it from the other party before marriage. These must be proven and verified, but I was taught they are all pre-Vatican 2 annulment grounds.
Perhaps Pax can corroborate.