Such an article would include a clearer picture of what marriage looks like: making decisions about career, where to live, how to spend money, how to raise children, etc.
All of this is compounded when you and your spouse are living for different things.
There is nothing wrong with building quality friendships with unbelievers, but that is as far as it should go.
If you were dating an unbeliever, what would honestly be your priority, romance or winning a soul for Christ? Is it wrong for a couple to live together before marriage?
The imagery is of two incompatible oxen sharing the same yoke.