There is a "No-Go Zone" (usually about 45 degrees on either side of the wind). If you point the bow too close to the wind, the air can no longer flow smoothly over both sides of the sail. The sail "stalls," loses its wing-like properties, and begins to flap like a flag.
Sailing is essentially a game of "aerodynamic tug-of-war" between the air above the water and the water below it. 1. The Sail as a Wing (Lift) Physics of Sailing
The boat "squeezes" between the wind’s push and the water’s resistance, converting that sideways energy into forward motion—much like a wet bar of soap shooting out of your hand when you squeeze it. 3. Apparent Wind There is a "No-Go Zone" (usually about 45