plus, the titans in the show are a completly different team than the team BB and ray are in when they finnaly get togather. by then, raven has been reborn into a teenager again, making her bbs age. in the original(what the shows based on), BB was the jr.titan and Raven was older and kept to herself more.Plus Kid Flash kinda had a thing for raven. BB had a thing for "Goldie"(what he called Starfire):)
Because the TV show never gets as far as the comic books did. I wish it would but apparently the creators ran out of money and couldn't continue the show. Sad story, but as Raven once said, "We can't change the truth no matter how much we dislike it."