Personally I wouldn't tie sex and marriage into one item. I think two people that love each other so unconditionally and passionately should not feel ashamed or bound by any taboo to share their bodies with each other and enjoy intimate experiences. It's all a part of the relationship growing. However, I'd only make love to someone I really felt strongly for. To me marriage is basically the fulfillment of a promise to remain with each other forever and to share responsibilities and the obstacles the world throws at us equally, but it is not necessarily about sex. Each circumstance is very unique to the individuals involved; I think you should do whatever feels right in your heart.