The only kind of intimacy allowed between a man and a woman who are not married but are planning to be married is spiritual intimacy. Since they are not married, they cannot have sexual contact, nakedness before each other, the touching of the private areas, or illicit discussion of sexual things. In other words, sexuality and physical intimacy are reserved for the marriage bed, period. I don't see any problem with kissing provided that it does not accelerate into a situation of temptation or lust.
- 1 Cor. 6:18, "Flee immorality. Every other sin that a man commits is outside the body, but the immoral man sins against his own body."
- Eph. 5:3, "But do not let immorality or any impurity or greed even be named among you, as is proper among saints."
- Col. 3:5, "Therefore consider the members of your earthly body as dead to immorality, impurity, passion, evil desire, and greed, which amounts to idolatry."
- 1 Thess. 4:2-5, "For you know what commandments we gave you by the authority of the Lord Jesus. 3 For this is the will of God, your sanctification; that is, that you abstain from sexual immorality; 4 that each of you know how to possess his own vessel in sanctification and honor, 5 not in lustful passion, like the Gentiles who do not know God."