The only parts that really matter and take commitment in wedding vows are; worse, sickness and poorer. Better, richer and healthy is pretty easy to deal with.
Promises that fade in time, are no promises - vows that lose honor in time, are no vows - love that wears off in time, is no love.
It's ridiculously easy to fall in love, even the animals can do that - what's hard is to sustain that love for life, which most animals can't do, but the humans can.