Alistair and I (a female human noble) were richly in love before the Landsmeet. Then he broke up with me so that he can have a baby with someone less tainted. I heard, as a human noble, you can have Morrigan do some ritual thing? How and when can this happen? Is it too late now that he already called it quits? I have yet to go to Redcliffe to battle the Darkspawn.
So the order here is... 1) Fall in love 2) Landsmeet 3) Alistair says we can't be together because of the darkspawn taint. 4) Morrigan performs ritual before the end battle. 5) ...We get back together, marry and live happily ever after?
Alister will break up with you if you are not a human noble persuasive enough to make Landsmeet accept you as the queen, if you want to continue with him just make Arona the queen. or you can always just have him killed (man how I loved having Alister executed). Morrigan's ritual has nothing to do with romance.
you didn't use the option at the landsmeet to have "alistair on throne and rule beside him", so you won't get married even being a noble woman.
morrigan will offer you the ritual regardless of how the landsmeet went, or who/what you are playing as. it's there for specific reasons. you've already marked this thread for spoilers, so I'll say that at the end, one of the wardens has to die. if you do the ritual with morrigan then no one will die. it's offered right before the final battle so it's a little ways down the road from the landsmeet.
if you decline her offer, stay in good graces with alistair and take him in your final party, he will sacrifice himself for yuo even after breaking up, and say he was a fool for leaving you
if you decline her offer and leave alistair behind, he will hold a nice funeral for you and talk about how he thought you two would be together forever, despite having broken up with you.
if you accept her offer then it won't matter either way if alistair is in the party - he will be crowned and at the end when you mention your past relationship about it he shows remorse about what couldn't be but will still carry out his duty - without you.
you could always just go back to a previous save and redo the landsmeet. up your cunning and coercion skills. use books if necessary.