I am voting no. The whole basis for Rhagaea's power is that she's the widow of the dead emperor, running things on behalf of Arenicos's blood heir.
It makes zero sense for Rhagaea to be willing to get married, because it would jeopardize her claim to power. She might be willing to let her daughter get married, but that's a different story. She wants someone sensible to marry Ira to be a good influence.
Alternatively, I can be persuaded that Rhagaea can be marriageable but you better be a dang important character before she's willing to marry you.