the league of villains have received the full attention of the pro heroes. due to this they figure that they'll be all in danger if they stick together. so Shigaraki suggested that pairs of two should lay low in separate hideouts in areas where there isn't that many heroes.with this suggestion made, Shigaraki put the pairs together. one of the pairs was Deku and Toga. with these two Alone together who knows what they would be up to until they reunite with the others.