Originally posted by: Terracosmo
I don't think Yzak & Shiho are officially a couple. As far as I know, Shiho is just his fangirl who idolizes him. Taking it from such a viewpoint I would deem it more likely that he'd spend time with his best friend Diakka when he gets some free time. This is however impossible to discuss since there's no evidence which points in either way yet.

Also, in the Gundam Seed - Towards a neverending tomorrow PS2 game, Shiho works under Yzak during a mission. I believe that is also in the Astray manga.

If anyone knows differently feel free to correct me.
I've never played the PS2 game, and I only made the arguement to say that the point I made is a possability. Obviously I have no proof for any of it.