The way Ser Duncan the Tall spoke to his horses—you would've thought Sweetfoot was his wife. Soft and honeyed, deliciously sweet. "Easily startled, they are," he would say, "need a bit of encouragement is all."
Any hint of skittishness and it's "it's alright, darlin'" or "that's my good girl".
And former noble lady/companion!reader is awfully jealous. She's easily startled too. She needs encouragement. She's a good girl.
Dunk doesn't know why his lady pouts whenever he tends to the horses. Why her sweet face goes red and she seems to upset.
Egg tells him one day, "You coo to the horses more oft than to her. It's insulting." Dunk, as thick as ever, responds, "I do not coo. And she is a lady, I cannot address her as I do the horses."
But the next time she startles at a loud sound or pouts about the stale bread, he tries it. His voice lowers and he's murmuring sweetly, "It's alright, darlin'. There, now, you're alright."
And the way she flushes and instantly quits her fussing is unmistakable. She quiets and she's all soft and pliant and his and he'd never stop speaking if she responded like that every time (she will).