Well, Ranka already said "it was because of me" when she got controlled by Grace. I know she was refering to the tragedy when she was young. And Frontier fleets got heavy damage when Ranka got controlled. But when Ranka got free, what do you expect Ranka to do? Self-blaming for half of the episode before she goes to save Frontier?? If Ranka did this, then there will be more criticism from Sheryl Fans XD....
Her action to save Frontier immediately could be a sign that she has learnt the importance of putting her power into the good use. She also embraces her responsiblity, knowing that it's her duty to not allow the tragedy in the past to happen again in the future.
Basically, Ranka has changed a lot throughout the series, from a normal teenage girl, to realize that she has the power to "tame" Vajra, to understand that tragedy can happen and ppl could be gone, to know that human and Vajra have to coexist (her adventure with her brother to the Vajra planet), to remember the tragedy, self-blaming herself before got controlled from Grace, to act immediately after freeing from Grace's control in order to save Frontier and realize that it's her duty to not allow past tragedy to happen again. I would say that Ranka does change a lot. Of course, her love with Alto hasn't changed at all. But romance and experience don't have to conflict with each other. Ranka can learn from her experience and love Alto at the same time. Ranka doesn't have to leave from the love triangle to prove that she has changed XD
The last thing I want to say is, Ranka is a special character in the series. Because she is the only one who has that "magic power", so she experiences lots of things that other will never encounter. Throughout the series, she has been trying her best to put her power into good use. She witnesses and remembers that tragedy can happen right before her eyes and at the end she acts bravely to save Frontier immediately.
Like I said in the last post, some audiences want to see Ranka suffer before allowing her to move forward, but in my opinion, Ranka has decided to move forward in episode 25. Ranka's mind has changed during the period she got controlled by Grace. We see a stronger-willed Ranka after she got free. She realizes the importance to act immediately, that maybe the reason why we didn't see she say "It was because of me" again when she said that sentence before Ranka got herself controlled by Grace.
Like Urei said, probably nothnig can change each other's opinion, so leave this Ranka tread to Ranka fans plz XD (so Ranka fan can have place to gather besides that fansclub....Ranka fans need to expand the territory somewhat
)