Well i'll pare Azmaria from Chrno Crusade with Gaara from Naruto. The reason that is Gaara is lonely like Azmaria(not anymore after she met Chrno and Rossette), but they have opposite additude (i'm not a good speller mind me) and behavior. Also she's hard working, caring, happy, and really emotional(same with Gaara). With these reason he could cheer up Gaara all the time since he doesn't cared about any1 much and always sad and violent.
Well its kinda weird for them to be couples cuz Gaara is like 15 and Azmaria is around 11-12. So what if their age is 3 years apart its still gonna work out anyway..... i think.