Frisk grins and blows a raspberry at Sans--no harm, no foul, dude! They have forgiven far worse crimes against their person before.

"You're bluuuuuushing! You do like her! It's okay if you're shy, Alphys and Undyne were, too." Frisk nods and crosses their arms. They totally have this match-making business in hand, they are a master at it.