These days, we say both “you and your fiancée / girlfriend get married” and “You marry your fiancée” (and she marries you). The reason we say “you and your girlfriend get married” (passive voice) is that it is someone else who performs the ceremony. For example, a justice of the peace married us = We were (or got) married (to each other) by a justice of the peace. For this reason, it used to be considered correct to say “I got married to my fiancée” rather than “I married my fiancée.” Nowadays, however, the latter is far more common. In English, we do not use the preposition “with” to talk about our marriage, although other European languages do.