I agree a lot with what Anna and Deanna have said.  You either trust someone or you don't.  Yes, trust builds a strong relationship, but has nothing to do with whether or not you have sex before marriage.  Where sex and trust intersect is when commitments are made to be monogamous in a relationship, and that very meaningful, powerful decision can be made anytime, anywhere.

My husband and I  have been married almost 12 years, and have been monogamous the whole time.  But we were just as monogamous together before we got married.  We made that decision and commitment and stuck with it.  Being married to him didn't earn my trust.  Keeping commitments does, about sex and everything else.