Virgos have high standards and do their best to live up to them. Their biggest fear is to fail to meet their own expectations, to be less than perfect, to hold the bar lower than they have previously set it. Whenever they feel they are no longer impeccable, Virgos would stress out.
Another thing is that Virgo never thinks too thoroughly before setting their standards – they just want them to be high, without assessing whether they are utopian. Most times, their flaws are simply invisible for people with realistic values and world views, so Virgos have to ease up.