Again, though, what is marriage, exactly? Is it not a committed, lifelong union between two people who love each other? If so, it sounds to me like they're married already. Of course, that's not to say that I think they shouldn't go ahead and get an "official" marriage, since being married before the state as well as before God obviously has several practical advantages, but at the same time I doubt that their current sexual activity can truly be deemed sinful, as I don't think it can truly be deemed extramarital in the first place.
God is all about deceny and order. He tells us to OBEY not only Him but the laws of the land. Obeying Him is first and foremost and when we obey Him, we end up not just keeping His commandments but we end up obeying the laws of the land, which keep us from having to deal with the consequences of disobedience.
We can twist God's word all we want to try to justify our actions by reasoning and rationalizing but that doesn't change the Truth of His word.
Bottom line they are not married yet and they are dealing with fornication. The definition of fornication is consensual sexual intercourse between two persons not married to each other. Here are some scriptures:
1Cor 6:17-19
17But he that is joined unto the Lord is one spirit.
18
Flee fornication. Every sin that a man doeth is without the body; but he that committeth fornication sinneth against his own body. 19What? know ye not that your body is the temple of the Holy Ghost which is in you, which ye have of God, and ye are not your own?
1 Cor 7:1-3
1Now concerning the things whereof ye wrote unto me: It is good for a man not to touch a woman.
2
Nevertheless, to avoid fornication, let every man have his own wife, and let every woman have her own husband. 3Let the husband render unto the wife due benevolence: and likewise also the wife unto the husband.
Gal 5:18- 20
18But if ye be led of the Spirit, ye are not under the law.
19Now the works of the flesh are manifest, which are these; Adultery, fornication, uncleanness, lasciviousness,
20Idolatry, witchcraft, hatred, variance, emulations, wrath, strife, seditions, heresies
1 Thess 4:2-4
2For ye know what commandments we gave you by the Lord Jesus.
3For this is the will of God, even your sanctification, that ye should abstain from fornication: 4That every one of you should know how to possess his vessel in sanctification and honour;
Since they are not married their sexual relationship can not be deemed as an extramarital. If they were married and had sex outside of the marriage then it would be considered adultery. The definition of adultery is voluntary sexual intercourse between a married man and someone other than his wife or between a married woman and someone other than her husband. This is not their case.
Yes they love each other and no one negates that fact. Myself along with some of the other posters on this site want her relationship to be blessed by God and God expects us to obey what He has commanded and for us to operate in decency and in order.
The church is so sick and weak (not operating in the fullness of God's power) right now because people have watered down God's word to fit their lifestyles and this is dangerous territory to be in. Since it's the truth that sets us free, we have to first be willing to accept the truth for what it is - THE TRUTH and the Truth is God's Word! We can't pick and choose from God's word to accomodate what we want to do, what we think, how we feel, etc. We need to let the truth penetrate our hearts and change us from the inside out.
I truly pray that God's corporate body will get it together and let His word be engraved in their hearts. Until we all get it together, the church will continue to be in the state of weakness that it is currently in.
God Bless!