Why doesn't ice form on the fuselage?
It does, but there is much less of it on the fuselage than on the wing.

There are two ways how ice is accumulated on the aircraft's structure:


When flying through air containing supercooled water droplets, the water will freeze on impact. It does not make much of a difference whether the water impacts the fuselage nose or the leading edge of the wings and tail surfaces: It will form a sheet of clear ice.
When flying through moist air at a temperature close to freezing, the pressure loss of the air flowing around any obstacle will cool it down, so the moisture condenses and, if temperature allows, will form ice accumulations. Those in turn exacerbate the suction peaks, leading to more ice being collected.


The wing's leading edge shows the most pronounced suction peaks, so they will collect most ice. However, if the icing conditions are right, the fuselage nose will also pick up it's share of ice. Along the length of the fuselage, pressure is similar to ambient, so it will collect ice only when sitting on the ground in freezing rain.



Iced engine nacelle in the NASA Lewis (now Glenn) Research Center icing research tunnel (picture source). Here, water is sprayed into the tunnel and forms supercooled droplets.

In both cases icing has nothing to do with the boundary layer - with supercooled water it is simple ballistics, while the second case of ice accumulation is dominated by the pressure of the flow around the aircraft.