Men and women communicate very differently. Research suggests that women may have at least 16 different tones of voice that other women can recognise but men cannot recognise. Hence men literally can’t understand some things that women say.
These different hearing processes between the sexes may cause men to drift off when listening to women because they’re not hearing the full complexity or gravity of what is being said. Also, there may be an element that men’s evolutionary brains, especially when speaking to women they’ve just met, are only pretending to listen, whereas in reality they’re calculating the most efficient way to get her into bed.
Female evolutionary brains on the other hand are looking for clues that the guy is likely to stick around. So women may well think that men aren’t listening to them because in reality they’re not.
These different brains and hearing processes do not get men off the hook though…