The Church's default position is that a marriage vow is valid and binding unless proven in a court of law to have been defective ; that refers to a constitutive element of a sacrament --- Marriage vows are binding, as Jesus Himself taught --- therefore the Church always has to presume the vows are binding unless proven therwise.
Now, the grounds for Annulment may vary. That's the part that can change --- within limits.
For instance, right up until almost the modern period, marriages were arranged by parents, and children could be betrothed (promised) in marriage even as minors. That was never grounds for an annulment. It would be now, though, since psychological maturity is much more emphasized as determining the validity of a vow.
Yes. It is my thought. My thought. That the annulment process is fatally flawed and part of the reason for so many Catholic divorces (along with poor catechisms and living in a semi-pagan country.). First, the legalistic nature of the proceeding, second the attempt to judge a state of conscience many years after the fact, third the horrible wait for justice. These are serious flaws that need to be addressed.