Hmmm.... overall I'm not sure what the answer is (and some of it depends on how you define single), but it seems to me Christians tend to fall into a few different categories:
1) Those who marry quickly because they want to have sex (or had sex and now feel they have to get married)
2) Those who have come to believe (through teaching or fear) that they need to wait for God to bring along the perfect relationship and are waiting on God darn near forever with impossibly high standards that even they don't meet.
3) Those who see sex and romance as a competitor to their loyalty and devotion to God.
4) Those "don't fit" the Christian mold and so feel stuck between no one in the church will want them and they don't want to date a non-believer.
On the non-Christian side however, there is becoming less and less incentive to get married at all. So I think maybe we can say that Christians have more hurdles to establishing a romantic relationship, but quite possibly higher quality relationships. And I think we'll have to define things a whole lot more to really find an apples to apples type of comparison.
For my first marriage at the age of 23 your #1 criteria holds true for me, especially the part in parentheses.
I made a seriously bad mistake that affected me for years to come. I should have considered her best friend instead. She had a thing for me but I was too blind to see. A Christian woman too. My X was a Christian also but perhaps in name only. Thinking back, that was probably true for me too at the time.
Marry in haste, repent in leisure. My mom told me that before I got married in 1978. She was right.
Horrific marriage. Bad. Lasted 6 1/2 years of pure hell, and she gave me hell for years after that and tried to thwart my attempts to remain a viable father to my daughter.
It's like my daughter told me a couple years ago, "Mom's not right in the head, that's why she treats me and my children like crap". I didn't say anything but just nodded my head slowly. Fortunately for my daughter, she doesn't remember much of the actual living conditions of our dysfunctional household. She was too young and was spared that.
My X once said that "We put the 'dys' in dysfunctional". That's about the only thing that she got right.