Did these two get along in real life? Were they friends, or romantic with each other? I thought they were such a cute couple!!! :D

Cute couple indeed, but Dick and Mary were both married to other people.
According to Mary, she had a very real crush on Dick. I've also seen out-take footage of Dick admitting that he was nervous because he was about to kiss Mary in the scene they were trying to film. According to both, they never had an affair. According to Barry, Dick's son, he's not so sure.
I'd say they got along fine!

Steve

Originally posted by FonzesLeatherJacket
Did these two get along in real life? Were they friends, or romantic with each other? I thought they were such a cute couple!!! :D

I agree, "Cute" isn't even the word for those two! From what I've heard in interviews, they each had crushes on the other. Steve's right, though, they never did anything about it. (At least, that we know of ;)) I like to think of their relationship as a "puppy love" kind of thing. They still get along well today. (The upcoming "Gin Game" is evidence of that!)

Hope that helps!