not to say that most of the time, it's the female counterpart that gives issue. it has to alot to do with the family upbringing. i have a lot of male Christian's friend who are strict as hell who claimed to only will date Christians and if there are none left in this world, they would rather not be in a relationship. You may be surprised but these people do exists.

either you have misinterpreted the contents of the post entry or that she is focusing on one part of the problem or she doesn't understand why the caveat is imposed in the bible.

the rationale behind Christian marrying Christian is simple and not rocket science, this is that it is in harmonious with the bible. the union between a male and female in God's light resembles Adam and Eve, with that, God can then bestow upon His blessings on them. it would be absurd if not contradictory if God blesses that individual who is not a believer or if He only bless one person but not the other. It's an union hence it must be fair. This is the "spiritual" side of things.

the more noble notion is that, assuming all Christians are devoted, understands the sanctity of marriage and will not commit sins against any of the 10 commandments. it is a general perception that non-Christian does not know about the 10 commandments hence, you cannot perform what you don't know. it's always better to have 2 people having the same thoughts live together than completely 2 people from different worlds, the latter would be a disaster friction waiting to happen. this is just basically, reasonableness.

but to be honest, none of these hold true anymore.