when good things just fall apart

some friends of mine are getting divorced...
this is the first time someone in my own peer group has come to anything like that.
all the people i've know to get divorced have been like..parents of friends..or people of that age.
this is so strange
i've seen them together
i've seen how much he loves her
i've seen how happy they were
or so it looked
i've seen so much that they've come through together.
things that i thought would make them stronger
but it broke them.
this is so sudden
so unexpected
dont you usually see this sort of thing comming?
i dont know completely what to think