For example, paper's structural integrity decreases when it comes into contact with a liquid. What happens at the time of contact?
In the case of paper, fibers are connect to each other with hydrogen bonds. Water and humidity affect to these bonds and the fiber matrix loses its strength, or integrity.
In a more general way, water molecules tend to surround the charged particles (atoms, molecules) as they are polar.
Now, let these "charged particles" form the bonds of the material => water molecules surround them => particles bond with each other rather than other particles.