"...and to save myself from the life limit of 5 years caused by mana maladjustment." While she certainly wants to save the others, the fact that a self-preservation reason is present is, in my opinion, very good. Shows that she's not a saint or truly selfless, just that she recognized it's in everyone's best interest, including herself, to try and steer the world in a different direction. It also helps that she actually likes the Emperor, so it's not all calculative in nature but genuine attraction. I'm looking forward to seeing how this will play out.