Entropy and spontaneity (Second law of Thermodynamics)

Look at the following examples:

i. The entropy increases when ice melts above 0 °C and when water vaporizes at 100 °C. Both are spontaneous.

ii. Consider the spontaneous reaction at room temperature:

The entropy increases due to the formation of O$_2$ gas.

From the above examples, it is clear that the entropy of the system increases in the spontaneous processes. But consider the reaction

$2\mathrm{H_2(g)} + \mathrm{O_2(g)} \longrightarrow 2\mathrm{H_2O}(l), \quad \Delta S = -327\ \mathrm{J\,K^{-1}}$ …