I don't really know what you mean, especially with being happy together? Like, most gundam couples I can think of either die off EXTREMELY early or survive and get to be happy. Even Shiro and Aina get their happiness at the end of the absolute doozy of 08th MS Team. There's plenty of other happy couples at the end, like Domon and Rain, Garrod and Tiffa(and all the other couples in X, really), Setsuna returning at the end of the A Wakening of the Trailblazer manga to de-age Marina and pretty unambiguously getting married, Marie and Allelujah, the list really goes on. Gundam has a pretty long list of happy couples, especially when half of the couple is the show's princess.