When does the marriage actually take affect? There are in affect many moments that signify the marriage: The engagement ring, the discussion with you betrothed parents, the engagement party, opening up a joint bank account for the gifts, the veiling, the chuppa, the wedding party, moving in together, and of course the sex.
According to some reads of Ketuboth, the process of marriage may take affect in stages, because the marriage itself is made up several different relationships - sexual, familial, economic, social.
One place this issue arises in on page 56a. If the husband adds on to the base price of the Ketuba, when does the wife actually acquire the rights to that money. The Gemarah tries to answer from a psychological perspective: what was the reason he added on to the basic requirement of the Ketuba? Does he promise it in order to make her happy to sleep with him, or because he is paying her to sleep with him, or he is paying for her specific level of experience or virginity- in which case she would only own this part of the Ketuba after they consummate the marriage. Or perhaps he adds the money to make her happy at the Chuppa, perhaps representing the more social or even communal element of their relationship. Then after the chuppa she would be entitled to this money.
In some ways this discussion raises the question: how central is sex? Does sex represent some kind of love and personal relationship that has already been initiated at the Chuppa. If so perhaps the promise of fidelity made at the chuppa is enough to solidify the marriage in that it hints to the consummation to come, based on the emotional (and legal) promises made. Or perhaps none of these promises and projections are meaningful until they are fulfilled and made tangible.