i have to concur with you... i notice it too... most people who got married at a very young age ended up getting divorced as opposed to those who got married at a late age like in their late 30's to 40's stayed married-- they seemed more stable/compatible, very happy and settled too... it is very rare for those who got married at a very young age to stay married... and be happy too.:
Yep, I noticed it also, because younger folks don't completely reveal their true colors until after they're married, they put on an act like I wanna get married, I wanna be a wife, and live happily-ever-after then boom they're married everything changes down the roads, and realized that marriage is hard, they don't have the freedom to do what they want anymore, they're stuck with the same guy for the rest of their life, and that's what frighten them, that's what I believe. I think they think being a housewife is a fun, but don't realized it's hard work, it's commitment.
So, I agree with you, about the certain age range 30's-40's are more maturity and wiser to have a stable long lasting marriage than the age range of 20's.
That's one reason why I waited on marriage when I was younger, It took me six years to say yes to one of my ex, but then just in a several months later I found out he cheated, that's how I learned that he isn't ready at the age of 23, either am I. If I never found out his true colors, I would had a bad marriage.