Soldato
Well a lot can happen over the years. People tend to lose focus , forgetting the number one mantra of always improving yourself.Marriage is an outdated institution anyway. Why anyone would want it is beyond me. Most marriages end up like the OPs anyway in this day and age.
What is wrong with just being together and not signing some paper and spending stupid amounts of money on something that the majority of the time is doomed to end up failing and causing more money/stress later on down the line.
Pessimistic I know, but true.
I also think people rush into it - getting married after a few years etc.
Marriage is a commitment and time needs to be taken to ensure compatibility is there especially in the bad times.
Also kids. Both a blessing and a curse. Couples forget to make time for themselves and each other and before you know it youv woken up 10 years later not having a clue who the other person is anymore!