You’re going through a separation and your communication with your co-parent is awful. You fight about everything. You’re wondering: ”How are we ever going to be able to agree upon major decisions about our children, and what are we going to do if we can’t make any decisions?” Your answer to that might be: ”Well, maybe I should just say I’ll be the sole decision-maker and I’ll ask for sole custody.” While that sounds rational to you, it’s not going to have the same effect on your co-parent.