I don't think she is 'keeping herself' for him. In the earlier chapters she said she isn't doing it because she doesn't want to get pregnant yet. And In the later chapters one of her consorts told there are other ways to do it without one getting pregnant and they were about to do it but then got interrupted.
So... yeah. But l also wish that they start doing it cuz this is just getting boring (〜￣△￣)〜
Fair enough! I mean she started the whole thing for emotional revenge and to hold off choosing a husband, but at this point she's leading them on lol
She's not keeping herself lmao that ship has sailed
She did start off a bit out of rage, but a lot of it has to do with political reasons too. She isn't leading any of them on (except the prince, initially) because they all know what they're they're for. Their own personal gain. It's just a transaction like any other. Noble families that conceived legitimate children of the emperor in the past have a history of assassinating them to usurp the throne and reign as regent so as to put their family in power. So till you stabilize your own situation it's better to hold having children off.
I wish this would start being a proper harem and not her still "keeping herself" for the coward Emperor who ditched her.