How do you get married on dragon age origins

you cant really get married but u can have a relationship with the characters in your party for example sex. Though if you have a strong relationship with Alister at the Landsmeet you can be betrothed to him by your choice only if you are a Human Noble ONLY!!! And when you defeat the Archdemon you have his coranation and then the epilogue and it tells you that 6 months later you marry him. But you must do the ritual with morrigan and Only Alister or (Logain if you agree to make him a Grey) can do it.