In this paper, we present a theory for strategic decision making on group collaboration under temporary constraints for avoiding de-escalation moves. Group negotiation has two types of decision making: collaborative and competitive strategies. The collaborative strategy is a type of decision making under which any player in negotiation groups would not leave from non-repeatable games of finite stakes on their possible agreements, while the competitive strategy is the other style of decision making under which any player in negotiation groups would leave for other repeatable games of infinite stakes on their possible agreements. Those two types of strategies are selective for increasing negotiated gains under temporary constraints in the response to properties of infinite and finite stakes on repeatable and non-repeatable negotiation games, respectively. The proposed theory provides decision support systems with the command of strategic decision making on group collaboration under temporary constraints by its static and dynamic analyses. Copyright 2008 ACM.