She looks at him, on the beach and knows that she has to love him. For both their sakes. To stop them both going crazy. He needs someone to rely on, someone he knows in this world that is so similar but so different to his old world, to keep him stable and out of harm. She needs someone to stop her from not stopping. She’s never stopped, not since the first time she was on this beach. Just constant rushing around, saving the world, saving the multiuniverse from the Daleks. Again.
She will love him, she just needs time.