Glimmer/Cato: Not bad, considering they're both careers. They were holding hands a couple of times, and Glimmer flirted with him a bite. They also snuggled up together when they were sleeping under Katniss' tree. They would have made a cute couple.
Clove/Cato: I don't think so. For them, it seems more like a brother/sister relationship. When Clove died, Cato was seen begging her to stay with him. They also had a bit of an age difference.
Katniss/Cato: Hmmmm...If Cato were a tad less brutal and bloodthirsty, he might have been ok for Katniss. It might be a little love/hate sort of thing. He would have been a bit like Gale, in a way. He was seen looking at Katniss a couple of times in the training center, and after the chariot rides. Maybe.
Peeta/Glimmer: No. I think Peeta and Katniss were made for each other. Glimmer is a little too...city girlish. Dictrict 1 + District 12 = Trouble. She would think he was a country bumpkin, and he would think her a city girl.
Peeta/Clove: Maybe, but probably not. Clove is a little too young for him, and he's not at all like her. They're not really cut from the same piece of cloth. I still maintain that Peeta/Katniss were meant to be together.
Thresh/Katniss: Perhaps. Katniss doesn't seem the type to like strong, silent people like Thresh. Peeta can be talkative when he wants to, and Katniss seems to need that.
Marvel/Clove: No. Marvel is a good fighter, but a bit dim. Clove would want someone with the same focus and bloodthirsty-ness as herself. Like Cato, but younger.
Marvel/Glimmer: Definitely not. Glimmer may be a bit dumb, but I think she and Cato would be better. As I stated before about Clove, he is a bit dim. Glimmer is pretty, and a good fighter. Marvel doesn't deserve her. Besides. They didn't seem to have any connections in the books or the movies.