At my Christian college, I heard this question all the time. It was used to determine if said girl should enter a relationship with said guy, and was also used between said girlfriends to discuss if said girl should date said guy. Now, I don't think it's a ridiculous question all together. If, for example, your heart is for missions and his heart is for business in the U.S. and not leaving the country, you have a conflict of interests and callings. Also, the question is relevant if you're determining whether he has the spiritual attributes to guide you in a godly, marital covenant. These are all legitimate reasons to raise this over-used questions.
Here is where I have issues with it:
It's used to such a degree, that guys and girls are second guessing relationships and marriage all together (at least that's the way I interpreted the question). It puts so much stress on the individual, often coming with the second clause, "...versus alone." Very few people want to be alone. And very few people in this world are alone. Marriage is a trend. A God-instituted trend.
Which leads to my argument:
Why would God say in Genesis that it is not good for man to be alone, or say that creation was very good after he had created Eve for Adam if marriage was not in his design? I have news for you: God is pro-marriage. Don't get me wrong. It is better to remain single and glorify God in your singlehood than marry out of desperation. That being said, God desires a man and a woman to become one flesh together, leaving both of their parents and starting their own family. This is healthy and right, and it answers the initial question of "can we better serve God together." YES!!!! God would not have created marriage if it did not better both the individuals involved and glorify Him, for it reflects the unity and love of the Trinity and can be a wonderful testimony of Christ's sacrifice. Therefore, if you find yourself with the possibility of dating a godly and wonderful man or woman whose heart is for Christ, glorify the Lord in your relationship and matrimony.
Times when this question actually works:
1) He's a non-believer- of course you can't better glorify God!
2) You're called to different lifestyles (see above)
Those are the only two reasons that come to mind. So I beg of you, don't let this question scare you away from a magnificent marriage that reflects God's love and allows two individuals to serve sacrificially, and daily, alongside one another.