Liked:
Ephram/Amy: Also wanted them together since the pilot and that never stopped. I loved the journey, and watching the two of them together was just really special stuff.
Andy/Nina: Also wanted them together from the pilot. Really enjoyed their shift from neighbors, to friends, to more. Another fantastic journey.
Harold/Rose: How can you not like them?
The most stable, consistent, lovely relationship. This was the kind of marriage I see Andy/Nina having when they get older.
Ephram/Laynie: They were cute together.
Fun banter, but just not meant to be. I wish Laynie stuck around. That was a rare misstep from the show.
Bright/Hannah: Mainly the journey to them getting together and for Bright to realize this great girl. Once they got together, though, it was obvious the show didn't really know what to do with them. Unfortunately. The journey was awesome, though.
Colin/Amy: I liked the tragedy of this, the maturity and devotion by Amy to stick around despite the coma, despite Evil Colin showing up, despite things collapsing. I really liked the backstory of a first love, and I really liked what they had before Evil Colin, and "Home" is one of my favourite episodes because you see that hint of what they were before the coma, the beginning of love and it's just so romantically tragic. I don't think I could have watched it anymore than half a season, it was perfect for the story the show had to tell. First love and then tragedy. It's mainly the backstory and "Home" that does it for me. Their exchanges in that episode ("I want to hold on to you, Colin", "you're just a jerk") are some of my most memorable moments in the series and some of the best written exchanges on the show. There's my mini-justification/defense.
Nina/Jake: I thought he was a good guy for Nina. Especially after Carl. Ass. I knew it was temporary, just like Colin/Amy, but I thought they gelled somewhat, although you could see they weren't quite made for each other and that Andy was better for Nina. Even Jake could see it.
Indifferent:
Agreed with Ephram/Stephanie and Amy/Reid. Barely even there.
Dislike:
Amy/Tommy: I didn't like Tommy. His eyebrows were too big and he was a jerk. Uh, that's all I have to say about this one.
Ephram/Madison: It took the show to a place I never wanted the show to go. Teen drama. I just didn't like them at all. Not once. Almost made me stop watching, and thank goodness I didn't.
Andy/Amanda: Ugh. Almost killed the Dr. Brown character. Just totally repulsive stuff. Not even compelling or interesting, just awful. I've never understood the point of this one at all.