Mourning a breakup is very much like mourning a death. In both a breakup and death, specifically when referring to a lover, something has been taken away from you abruptly. the first stage is shocked and, as I've known with death, people tend to act calmer right at the beginning when the physical void is still new. Deep sadness comes after. You dream of this person constantly only to wake up to find yourself alone and that is by far the worst feeling. When you realize there is only one reality and it is the one where you have still lost that person that you love. From here, it only get worse of course, when your typical day, which included this companionship, becomes lonely and more mundane. No more expecting a call or text or visit to break the weekly routine. No more dinners, holding hands, no more falling asleep next to someone to protect you. No more us. How long does this stage last? It all depends on the strength and resilience to move forward. In death, you cloud your mind with the things you could have done when that person was alive. Things you didn't say and should have said. Any regret you had during life is now multiplied during death. Same happens in a breakup. What you could have done or not done to make the love stay and flourish. Or when you should have broken it off to not suffer now. However, death is not premeditated, but break ups usually are. The only thing to remember is that time really does heal wounds and that what is unbearable now we come to accept with time. Eventually moving one and looking back without regret.