In relationships, it's better to pick a mate through wisdom rather than emotion. In order to get the right result in math, the order of operations have to be followed. If you add something before accomplishing the multiplying and dividing, the answer just won't be right. It has occurred to me that the order of operations if critical in dating and romance, too.
If we meet someone we really like emotionally, but who isn't saved, it is folly for us to give our emotional core to them. God tells us to, "seek first the Kingdom of God and His righteousness," and as a part of that, we need to put the spiritual health of the other person BEFORE dating and our emotional desires.
If we don't do that, what we're really doing is setting an immediate example where our own wants are equal or superior to God's desires and plans, and we show that our emotions trump the other person's spiritual eternity. We should make disciples first, showing integrity and sincerity of our beliefs—this will reveal just how much we love God, and will be much more effective at causing faith in those we love.
"For the entire Law is fulfilled in in this one word: "You shall love your neighbor as yourself."—Gal 5:14