THANK YOU. YOU LITERALLY READ MY MIND. this is exactly it
Well if you look at the whole situation, all those "men" around the crown prince would be delighted if the secretary became the Empress. Because if not, it would be a hell for them to live without worries...
So the problem would be only to women who (who knows why) wanted to marry the prince. Though an approbation from their own father would have been asked and well, I don't think any father wants their child to be killed quickly. So in the end, the secretary would be the best choice from the society's opinion. She is able to soften the prince, which help any officials ministers to be safe. The prince won't even look at any other girls and will be always with his secretary : a lonely wife life for the promised. And last point, the secretary is talented enough in their opinion (since they are relying on her so much) to hold the position of empress.
To conclude, the society in itself won't be a problem. Only from women's side would there be problems.
He's not the crown prince, he's the emperor already, lol.
But anyway, hm, while I completely agree that her becoming the empress would absolutely make those men's lives easier, I'm not sure they all realize it, or that they'd ever be able to readily realize that on their own, without some firm "encouraging" (read, "threatening") from the emperor, lol. Most people would think of the position of the "emperor's secretary" as a completely different thing from an empress (and thus they would probably react differently to a secretary suddenly gaining the authority and power of an empress). If a secretary that they have no influence on nor any ties with suddenly becomes the empress, they might change their tune and feel uneasy, becayse unlike the secretary position, the empress position is *permanent*: if they ever come to dislike them, subjects can find ways to induce or force the emperor to fire a secretary and/or replace her with another secretary, but empresses are not so easily removed from their post.
While it is possible and easier for unhappy, greedy, corrupt or jealous subjects to get rid of the emperor's secretary (if they ever come to dislike her, or, if she becomes an obstacle in their plans) it is on the other hand quite difficult for the same subjects to get rid of an empress that doesn't give them what they want or whom they have come to dislike. To convince the emperor to replace a secretary, an unhappy subject may just easily frame her with some grave mistake or wrongdoing, or just trick the emperor into believing they've found him a much more "suitable" candidate... but those schemes wouldn't work on an empress, because the empress is not as easily replaced just because she's fallen out of favor with the emperor... This is because, the secretary has no authority of her own: she is supposed to act as a mere spokesman for the emperor (if she ever disagrees with what he says, she can only try to convince him to change his mind... but if that fails, she can never go against what the emperor says, nor tell people a different thing from what the emperor told her to say). The empress, on the other hand, has a lot more authority and power of her own, and she might even have a lot more room to disagree with the emperor, since she can *pressure* him into considering other views on any matter by using her more powerful connections (or even the favor of the public for her , due to her public role as his legal wife).
For all of the above reasons, it is definitely likely that people who like "Rosalyn, the secretary" would treat her different if the emperor let it be known she can sooner or later turn into "Rosalyn, the empress"... and it's even possible for some of the more anxious along those people to one-sidedly start disliking her, merely out of the extreme anxiety and uneasiness of suddenly seeing her climb so much more higher above them, in the social and political hierarchy.
He's having a hard time because he never made his feelings clear to her before. That's partly because until now he avoided even the thought of dating anyone at all, as a way to avoid and delay any political discussions about him finally getting married... And the reason for him to dislike the topic of his own marriage so much (to the point that he even avoided dating) is probably because until now he has always dreaded that he'd inevitably end up forced into marrying someone he doesn't like, in exchange for the most convenient political alliance (and that this someone would have to be from a family probably a lot more powerful and/or "a lot more convenient as a political ally" than Rosalyn's own family...).
So... he's been avoiding the issue. And now telling Rosalyn he likes her out of the blue would probably be too much of a shock for her, since she probably knows better than anyone that the emperor can't just marry her without a real excuse, if she and her family happen to lack enough of a high social and political position (to be able to keep all the potential "rivals", and their *powerful* *families*, quiet)... He *knows* she's never even thought of the possibility of marrying him before, and that suddenly being told he wants to marry her would be a shock, since for her (as for any other woman) marrying the emperor (the top person in power in her country), of all people, would certainly be life-changing. He'd also need the approval of her parents (at least on the surface), when he hasn't even met them, nor ever had any direct business with them before...
Moreover, even if she was to agree, there's still the matter of getting the rest of the powerful people in their society to accept it. If Rosalyn's family is not powerful or prestigious enough, and the emperor marries her without a pretext, he'd be at risk of losing the support of many of the people currently keeping him in power (because those people would be expecting him to marry someone from a family whose prestige and power could help him strengthen his position as king, rather than weakening it). Both the emperor and his supporters would have to know that him marrying a girl from a relatively "average" family (without enough social prestige and political influence) would weaken his power (unless he finds a way to counteract it), since the noble and powerful families who'd had ambitions of gaining access to the top of goverment (by becoming the ones to succeed in marrying their own daughter to him, in a political alliance) would say he was being unfair and playing favorites, and maybe use that as an excuse to rebel (and as a convincing argument to get others to also rebel) against his rule, even.
So... it's not an easy matter, people. Not even tyrants can take the matter (of their own marriage) as lightly as many of you seem to assume...