Joan knows that Ted would happily help her into bed even if it hurts him, so she's grateful Sherlock is here to do it, if just to protect Ted.

When he climbs into bed next to her, she leans her head on his shoulder for just a moment, an affectionate gesture that she keeps brief out of respect for the agreement they've made.

Sherlock hands each of them a bowl and a fork, then takes one for himself.