So, basically, you guys believe that you shouldn't do any physical thing before marriage. Like Poohbear said, kissing, touching, and other things of that nature does not have to be sexual. In fact, they are great ways of showing emotions.
To address the second hand of your post, masturbation does not have to be that thing that sets people up for sex. The reason why I say this is because I know people who can't masturbate, and don't masturbate because it opens the door for sex and lust.
However, I know those who do do it becuase it closes the door to sex and lust.
However, let's just define fornication. Here is an interesting christian article about fornication:
http://www.christianlibrary.org/authors/Douglas_R_Young/misc/fornication.htm
"The majority of our Greek authorities are generally in line with one another as to the meaning of the word fornication. Fornication is derived from the Greek word, (pornea) and refers to some form of illicit sexual intercourse in general. Fornication can be committed between a man and woman, a man and man, a woman and a woman, or a man/woman and an animal. Our English term “pornography” is also derived from this Greek word. Webster’s Comprehensive Dictionary (Encyclopedia Edition) defines fornication as “Illicit sexual intercourse of unmarried persons.” Though this term is most commonly used to describe sexual relations outside of marriage, it is not limited to unmarried people because Jesus allows “fornication” as an exception to scripturally divorce a spouse (Matt. 5:32, 19:9).
Therefore, a married person can commit fornication just as an unmarried person can."
So how would masturbation fall into the category of fornication?