Sometimes, her shields come down. Sometimes, the ice she's allowed to crystalize and harden her heart melts, as something reminds her of him-- a flash of exactly the right shade of blue, the word wizard interjected into a conversation, a song on the radio, a particular lilting accent. And she closes her eyes as memories flood her mind, of light and happiness and holding hands while running in a rainstorm, and how he would crush her in a bear hug so tightly she could feel his single heart beating in his chest, how he would lift her off her feet and swing her around, how they were that inseparable team, saving Earth side by side, the other Earth, the one that she had finally started to call Home. She shudders under the weight of loss in those moments, and sometimes there are tears, but only for a moment. Then she will dash away those tears with impatient fingers and steel herself once again, live in the moment, Rose, that's all in the past, can't change it, can't make it better. Move on.
And so she does.