Even then, there are 18 year olds I've met that have the maturity of a 25 year old and 25 year olds that just don't seem to have a frontal lobe. Age is an important heuristic but certainly not the only important factor when you are thinking about emotional maturity and power dynamics in a relationship.

Someone signing a lifelong legal binding agreement at 18 is pretty wild

Like getting your driver's license and heading on the autobaun first thing

Just because you can doesn't mean you should

18-25, 7 years. That's half their current life and basically all they can remember. Just to the point where you should really think about marriage.

No one should feel obligated to get married. If that person cannot wait 7 years to tie the knot then they aren't ready for the rest of the ~55+ years.