hide one's head in the sand
Also, bury one's head in the sand. Refuse to face something by pretending not to see it. For example, For years we have been hiding our heads in the sand, refusing to admit that the store is losing money, or When it comes to a family quarrel, Dean just buries his head in the sand. This expression, transferred to human behavior in the early 1600s, alludes to the belief that ostriches burrow in sand thinking they will not be seen because they cannot see. In fact, however, when they do this, they are consuming sand and gravel to aid their digestive system.