"I have better people skills," she says, leaning back against him and squeezing his arms. "Sherlock has gotten better, though."

Clearly Sherlock deduced something about Ted that upset him. Something that he was keeping secret, not just from Sherlock but from her, too. It worries Joan that he feels he can't tell her. But there's little she can do about it. He knows he can tell her when he's ready.