His temporary mirth is indeed temporary. It evaporates in an instant as she reminds him of the central problem, bringing him to make a face, one of deep unhappiness.

Then suddenly, the cane is spinning. It takes him a second to guess what's about to happen, but it's overridden by the sudden rush, the adrenaline over the possibility of a real fight mixing and entangling with that choking sense of jealousy. The cut of the blade through the air, the weight of it in hand, the feeling of swinging out... There is, he thinks, one single thing he hungers for more than those around him.

And then he shakes himself of that, ridding that longing look for one of firm resolve. "I can still take you with a knife. Lets do this."