This is because Islam forbids sex before marriage or anything leading to it. If everything goes well, then the two parties agree on a day to make the marriage contract which should be implemented by a licensed Muslim scholar who would make sure that the girl has approved of this marriage and that she is going to receive her rightful dowry which is an essential part of every marriage contract. It is the right of the bride to receive her dowry, no one is allowed to take it or any part of it without her permission. Both sides then prepare for the marriage ceremony which is in fact a big dinner party attended by friends and relatives of both sides. This is usually given by the bridegroom's family.
Food is served in two separate halls and gifts are presented to the couple.
Songs are played and female friends and relatives would dance for the bride in the presence of women only. No men are allowed in. The groom would have prepared the future marriage home and the couple would go on a honeymoon trip according to the groom's financial standing. In Islam the wife does not have to change her family name to adopt her husband's family name. She has full right to keep her independent identity.