Originally Posted by Tony Stark
I think the Jane thing will be a side story, the main point will be saving the realms, but part of this will be Odin and Frigga's disapproval of Thor courting a mortal, and the strain between Sif and Jane. Sif loves Thor, and probably Sif is who Odin and Frigga want Thor to be with.
Malekith will threaten Earth which draws Thor as it's protector. Side plot will be Thor and Jane, the other side plot will be Thor needing Loki's help. In fact I'd venture that Thor and Loki will be more of a major plot than the love triangle.
That's pretty much the way I would want the movie to play out. Of course with both side plots being tightly interwoven in the main plot, which the trailer shows is the case.