To make things trickier still, some non-Christians have higher morals, and are more faithful and understanding than their fellow Christians.
It's a dilemma, and it does seem unfair of God to restrict us to the few that are Christian in the real sense. In the end it distracts from the real meaning of Christian life.
But there are many more stories to the contrary of great heartache and eventual splitting of partners either before or after marriage - sometimes much later in life.
With the added pressure of other people drifting in and out of casual relationships, everyone else is having all the fun and you end up wondering why you don't try it yourself!
The most important piece of advice is that saying he knows Christ doesn't mean he has a relationship with Him.