Illeitimus,Leliana doesn't engage in adultery because the wedding never took place because Lord Vaughan packed off the wedding party including the bride to be. The CE rushes to save Shianni and the Elvan maidens from harm and kills Vaughan for his misdeeds and for raping Shianni and they return to the Alienage with the freed maidens.
But all is not well.
Soon the guards show up and wants the names of those responable for the murder of Vaughan,the CE steps forth and confesses and before he is carted off to the castle's dungeon he is conscripted by Duncan into the Greys. The wedding is called off since wardens can't have families..
If the CE is a female then she gets packs off to the castle with the wedding party. Soris and the groom goes to her rescue and Soris gives her a sword and on her way to save the maidens she sees her groom killed, later she finds Shianni been raped and she kills Vaughan.. The same scene as above takes place except the groom is dead..
Alistair says roughly the same as Leliana.. Married? You never told me you're married.
As a side note She finds the wedding ring that her groom made for her.. In my games she keeps it and still has it when she goes to Vigils Keep in DA:A.
Sorry,but, I just gotta ask.. You never played as a CE?
In my games this hardens Tidus and Camine toward human nobles and Howe and Loghian adds fuel to that fire.