Spare somebody’s blushes
Definition 1 of 1
Pro Tip 1/3Cultural Sensitivity
Consider the culture when using the phrase to ensure it's appropriate and understood, as perceptions of embarrassment vary. 
He quietly pointed out the typo in her presentation to spare her blushes.
Pro Tip 2/3Subtle Kindness
This phrase implies a kind action done subtly to avoid drawing attention to the person's potential embarrassment. 
Her friend adjusted the price tag on her dress to spare her blushes before the photo.
Pro Tip 3/3Not Literal
The 'blushes' part isn't literal; it means preventing any kind of embarrassment, not just blushing. 
The teacher didn't correct him in front of the class to spare his blushes.