He was actually quite good at guitar--Ilya, nail on the head. The young lady was his new fiance, and I think she was getting sick of us ruining their time together.
A great street shot, and yes she does not look exactly thrilled, maybe he just can't get that B string tuned correctly.
Out of curiosity, why wide open on the aperture? It looks like the plane of sharp focus is on his hand and the headstock, because both people are soft, him especially.