When are a couple married in the eyes of God?  I think that it is when the couple actually consummates the relationship.

Traditionally, if the marriage was not consummated, then the marriage could simply be annulled.  Biblically, Jacob thought that he was marrying Rebecca.  And while Jacob thought that he was making his vows to Rebecca, he slept with Leah and thus, she became his wife instead.

While vows are nice, ultimately the marriage is made in the bed.  In short, if you sleep with her, you have taken for your self a wife.