Why doesn't nitric oxide react with water?
Although nitric oxide is thermodynamically unstable, it is kinetically stable as its decomposition rate is very slow[ref] and so it is considered stable and won't normally react to anything. 

So, nitric oxide wouldn't normally hydrolyze easily. But in the presence of air, it forms nitrous acid $(\ce{HONO})$:

$$\ce{4NO + O2 + 2 H2O -&gt; 4 HNO2}$$

However, nitrous acid is very unstable and quickly disproportionates:

$$
\begin{align}
\ce{2 HNO2 &amp;-&gt; NO2 + NO + H2O &amp;(cold dil. soln.)}\\
\ce{3 HNO2 &amp;-&gt; HNO3 + 2 NO + H2O &amp;(warm conc. soln.)}
\end{align}$$

Since $\ce{HNO2}$ is required to prepare diazonium salts (a versatile compound in organic chemistry), it is prepared in-situ by reaction of $\ce{NaNO2}$ and $\ce{HCl}$. Due to its instability, it is prepared for one-time use and is not stored for further preparations.



Reference: J. Phys. Chem., 1958, 62 (3), pp 360–361 https://doi.org/10.1021/j150561a030