If she had left without saying goodbye, he definitely wouldn't have taken it lightly. It's maybe for the best that he doesn't know how close it came to happening, that she only showed up there because of Beard. He understands the pain she was going through, but leaving him out of the decision, or at least not giving a proper goodbye, would've been a pretty huge betrayal to him. Even if she didn't know about his father, she knew about his wife.

Ted chuckles at Sherlock's comment. "Wanna get the wheelchair?" he asks Joan. She might want to try to walk the rest of the way now she's caught her breath, but he definitely doesn't want to assume that. "You can wheel yourself, if you want," he adds. Then she won't risk falling over or exhausting herself, but she'll still get to control where she goes.