save (one's) blushes

To prevent someone from feeling embarrassed or awkward. Due to your family's great service to the crown, we will save your blushes and not create a public scandal around this debacle. I tried saving her blushes when she asked me to prom by saying I had no intention of going with anyone.

save/spare somebody’s ˈblushes

(informal) not do something which will make somebody feel embarrassed: Don’t tell everybody about his excellent exam results. Spare his blushes.

A blush is the red colour that spreads over your face when you are embarrassed or ashamed.