I was kinda awed by this randomly visiting on the official forums and well this came up
How does that even work? Like okay half dragon half human.. um kids if they do actually be together yada yada. This lore's killing meJaina first met with Kalecgos when he was searching for the stolen Focusing Iris. During that time, they quickly became friends while they talked about their pasts, finding out that they share the same pain of losing someone they loved. As soon as Kalecgos left, Jaina began to realize that she missed him. When Jaina was about to flood Origrimmar in retaliation for the destruction of Theramore, Kalecgos was the only one able to calm her down, reminding her that she wouldn't stoop as low as Arthas during his culling of Stratholme. After Jaina became leader of the Kirin Tor and Dalaran, both she and Kalecgos started dating. - WoWpedia