bay at the moon
bay at the moonor
howl at the moonLITERARY
If you bay at the moon or howl at the moon, you waste your time and energy trying to do something which is impossible or trying to get something which you cannot have. You're looking for the perfect man and he doesn't exist. You're baying at the moon.
bay at the moonclamour or make an outcry to no effect.
The barking of dogs at a full moon has been a metaphor for futile activity since the mid 17th century.