Stonewalling is a turning away; a refusal to communicate or cooperate. Such behaviour can occur in any relationship. Body language may indicate and reinforce this by avoiding contact and engagement with the other party.
Stonewalling is a defense-mechanism that is activated when someone feels threatened or unsure as to how to respond to conflict in a relationship.
People who use stonewalling may do so because they fear a negative negative outcome or as a learned behavior pattern that they are repeating from childhood.
So, if you are feeling flooded and stonewalling, take a break using whatever signal, word, or phrase you and your partner have decided upon. Walk away and soothe yourself.
But then do return to your partner afterwards, make a repair and reengage.