This is also my experience: I was 22, she was 19 (married 10 years now). We finished school (3 BS, 1 MS, and a PhD between the two of us) and worked before having kids. I feel like we got married before we were each too stubborn and set in our ways to change. We met in the middle and grew into a single individual, greater than the sum of its parts. My (non-scientific) feeling is that in general, those I know who waited to get married had a more difficult time assuming a new identity that incorporates another individual.