Well, it's mentioned in the post-coronation paragraphs in LWW that there were plenty of suitors for both Susan and Lucy. (None of them, apparently, were married in HHB, which was about twelve years into their reign, wasn't it?) However, it seems that they were quite happy to remain as they were, ruling together as co-monarchs. There is no hint that anything had altered (or any of them had altared?) when they were hunting the white stag.

I think it would have posed major problems for them if they had been married, and then gone back to being children in England. To be sure, they would have been well widowed by the time they returned in PC. But it almost makes you wonder if that couldn't have been a factor in what ultimately went wrong with Susan? Not that she had actually married, but that it had made her think along those lines at such an early time, relative to her stage of life in England. Or maybe not.