Link's actually quite good with horses (not sure if you're familiar with Breath of the Wild, but one thing he does is literally just...go running around catching and taming wild horses). But for some mysterious reason, Muffin's much better behaved for Link than she is for the Doctor... :P

Haha yeah, awkwardness all around here! Honestly Link has very little remembered experience of like, social norms and living in a society. He doesn't have a great concept of 'normal', so he tends to just roll with other people's weirdness.