Our initial reaction to any sort of rejection is hurt, it's human nature. The three basic stages of rejection are anger, thoughts of revenge [especially for the Scorpios reading this ], and then sadness. However there's a fourth stage, it's called being Amiable. Friendly to yourself and to them.
Why the hell would you want to be friendly to the person that broke your heart or shut you down? Because it's NOT for them, it's for you. Holding animosity in your heart has negative ramifications; health issues, it negatively affects, holistically, other areas of your life, and stagnates your emotional progress.
Albeit, I'm not suggesting you send them a teddy bear and flowers or help them match socks. I also am not so naive to think being amiable, in the face of remorse, is an easily accomplished task. However, as soon as you can wrap your mind around a "rejection is protection" attitude you can begin to move on and start over. Whether it was a new love or long term relationship that unraveled, the sooner you can see the comedy in what happened or, at best, "the lighter side", the sooner you can begin to get back to the old you. You don't need to show them that they are forgiven, you don't need to be outwardly friendly to them, but in your heart you need to find a neutral ground where they no longer affect you. You most likely will not get any sort of closure from them so the onus will be on you to find peace within yourself.
Most, but not all, of rejection is a blow to our ego. Never underestimate how powerful a bruised ego will affect your outlook! It's usually a combination of things that make us feel badly after a "shut down" and you may want to pick away at the feelings you're having so that you can put each one to rest one at a time.
Situations where you'll need this tactic:
1. You ask out a girl and she says no
2. You're boyfriend / girlfriend breaks up with you.
3. A mutual break up
4. You begin dating someone, everything seems to be moving ahead, and abruptly ends.
If the relationship, long or short, had any sort of depth, you can try to talk to the person just to get stuff off your chest. You should let at least a week go by before you attempt this. However, if you're in a "fighting mood" or if you're looking for them to say the things you want to hear, don't make that call. Also, don't do it via text, email, or in person. This is a phone call only situation.
A friendly reminder that there is another way to deal with rejection if you can find the strength and insight.