Here is information about marriage in Harvest Moon.
To woo the lady of your choice, you must first of all give her the gifts you like but you also should answer her question that she asks in her particular season. You can also enter and leave a building or vice versa and have her ask the same question. Thus, you can woo the girl of your choice rather quickly in this manner if you chose to do so. Once you have the lady up to five hearts, you can purchase a blue feather which you must give to her at a special time.
After you are married, each wife will take on a new graphic. They will wear a lavender dress with an apron, and have a similar hairstyle. The only difference will be the hair color. Each wife will do a different thing once married. Nina will do laundry, Ann will make inventions, etc. If you go to sleep after 5pm, you will lose affection points with your wife. If your wife is Eve, then you will lose affection either way. The best way to counter-act this is to give your wife an egg everyday so you can work all day. Your wife's likes and dislikes will change after you marry her and she will like eggs.
For more info about the bachelorrettes, see the characters section.