I sadly can say that I've read a few theories as to what the outcome is and am trying to see how they will spin it. I'm not giving stuff away here without spoiler boxes and since its all rumors, I'm not sure if it is even worth the effort to type it out.
My favorite theory that is not likely true is that after talking to DeAnna, he realizes that Gillian is the one he truly loves and he goes after her. She was my favorite from the beginning.
I love my awesome crazy wonderful friends!!
"Do you remember in kindergarten, how you’d meet a kid,
then 10 seconds later you’d be playing like you were best friends?"
I loved Gillian too and was so sad that he let her go. After watching the previews for the finale from the first episode, I am 99% sure it is Melissa he picks. The girl is wearing an ice blue dress -- more fitting for her coloring than Molly -- and has dark hair. I think the whole Deanna fiasco will last about 5 minutes. They have shown MANY times how sneaky they can be with editing the "coming up" stuff so I think they have made way more out of he Deanna stuff than there really is.
Another reason I think he picked Melissa is the preview they showed for the After The Rose show. Makes it seem like they are having it "private" so he can meet her parents without an audience around.