The whole idea of marraige is traditionally forced and is not completely legitimate and divine idea, as it is reinforced by all the major religions.
The requirements to meet for two individuals to "marry" is mind boggling and nonsensical, to an extent in my opinion, that impinges on an individual's rights.
But we all have seen or heard of really successful marraiges, alas we see these relationships in a light we wish to fantasize in. These relationships have a very proper chemistry of both love and friendship associated with them. THEY ARE NOT ALWAYS PASSIONATE AND DRAMATIC TO KEEP THE MARRAIGE GOING.
Believe me, the virtue of friendship in understand and practicality is greater than love. Love is just a stubborn obsession one can't seem to rid themselves of. Unfortunately in most cases individuals don't even meet the ideal criteria of love and they marry.
And finally I believe your friends married a little too early. They were naive and unlearned, but innocent.
Marraige at 16 in eastern societies work, because it is super cemented by the society and family around them, and obviously not what you call "love". For their well being the partners, although not in love, will over time develop friendship and thus they are happier.
One way to be content most of the time in your relationships is to expect the minimum from them. Exactly the opposite is done in western idea of "love". This makes love even selfish. This is true in 99% of the people, whether they like it or not. It is more about them than the people they love.
Anyways, I better stop, I am starting to sound wierd.