Rose would be a tad sad, yes, but more along the lines of hopefully; heaven knew that she probably would never develop a Sara in her reality--but a tiny, hopeful voice in her heart still protested, no matter what her senses told her. And Rose knew what it was like to be shunned by a parent from another world, another time, and have them not even blink.
The worst feeling in the world is to be unwanted. So, yes, she'll shower Sara with all the attention she deserves. And frankly? She didn't care if The Doctor did or not. She was her own person, as he was his own person.
He ran off. They were always running. Well, she used to run about too, but Rose wasn't the same teenage girl anymore. She ran anyway. Because running with The Doctor was better than nothing.
"I'm not really hungry!" Rose called out fruitlessly, rolling her eyes as she quickened her pace.