Marriage For Cash, Divorce For Darkness:

Okay, getting married isn't hard at all. It'll cost a wedding ring, though but you'll gain it back.

Wear your most attractive clothes in town, and try to find someone with a heart over their head. Flirt, Sexy Hero Pose, and Manly Arm Pump are the only three things you need to do to make her love you. Once her heart is huge, it will fade in and out. Give her a wedding ring and it turns golden. Buy a house and lead her there. She'll ask to get married. Say yes and a cut scene appears and you'll find that you have a dowry of several thousand. Once married, hit her. You'll be divorced almost immediately and gain 600 Dark points.

You can have unlimited wives.