I don't agree that they should divorce for that reason, but I DO agree they shouldn't tell single people to let God be their spouse. To do so is condescending. And that goes for pastors telling their single sheep this too. It is hurtful and does not bring us together as a flock.
It is SO amazing the hurtful things Christians tell one another, in the name of Christ.
It's because they're going through something they can't relate to, so they don't take the time to consider their words. I know most of the time they're trying to be helpful, but they need to get their theology right, otherwise what they say will do more harm than good.