It's complicated, but the answer is: it's mostly allowed but not necessarily encouraged! If you serve together (for example, you're both in the same squadron), it's absolutely not allowed. If you serve in different divisions (for example, a Khehi Ket who's an assassin or spy versus one who's a soldier) and you never see combat together or are assigned on missions together, it's generally okay, but it's definitely a case-by-case basis. And if it ever progresses from hooking up/casually dating to having the actual intent to marry, you have to ask your Drasil (basically your president/ultimate commanding officer) for permission to marry, and it's typically seen as a nerve-wracking thing. But there are plenty of Khehi Ket who are no longer active-duty, have earned retirement, or are in the reserves, so it's not generally seen as a conflict of interest and in those cases it'd be okay! So it just depends! But in the Khehi ranks of the Rebellion, it's definitely seen as something people who play fast-and-loose by the rules do and is a bit taboo. Generally, the idea of the perfect loyal upright soldier that gets hammered into you during basic training doesn't involve fraternization, lol, and there's a bit of cultural friction against it, but it does definitely happen!