Joan is so grateful that Ted doesn't quit. It had likely saved his life, yes, but it had definitely saved their relationship when Joan believed she had to leave Ted to protect him.

(And now Joan has to wonder what her leaving for his good and without asking for his opinion felt like to Ted in the light of what she now knows about his father.)

Sherlock watches them for a moment before saying, "well, come on. The smoothies aren't going to smooth themselves."