How can I deal with separation anxiety?

You can deal with separation anxiety by staying in contact with the person you are separated from, or try some breathing exercises while thinking of memories about the person/place/thing you are separated from.

Oh, I have such terrible separation anxiety! Sometimes I am labeled "clingy," but it's much deeper than that. What has helped me has been exposure therapy. Incremental exposure to separating from somebody I love, especially romantic relationships. Stay busy, re-frame your thoughts, keep a journal. If you think you have abandonment fears that interfere with your daily life, certainly seek and counselor. Don't feel down on yourself. Researchers at Haverford College, in Pennsylvania, found people who missed their partners when apart from them were more committed to the relationship, worked harder to take care of it and avoided damaging behavior such as cheating.

Talk to people regularly, tell your friends about it, make sure they know why you don't want them to leave :)

Try to surround yourself with people who you care about, and who care about you. It'll help distract from the loss.

I try and accept and remember that I may be physically separated it doesn't mean that I am emotionally!

One positive thing about todays generation is the internet. It is easier to communicate with somebody you haven't seen for awhile. It might make you feel better to snap chat with someone or even Skype because even though they are not physically with you, you still get to see them and here their voice.

Try to distract yourself as much as possible when whoever that you are attached too leaves you. Video games, reading a book, listening to music, watching television, can all help you! :)

In my opinion, I would change the way I do my routine. The more occupied I am, and do things I love, I start to get better.

The best way to deal with separation anxiety is your way. Find what makes you happy, and keep in contact with the person you are no longer with. Sometimes talking with someone to often can be a problem, as well as a big disconnect, you want to find the adequate amount of time to dedicate toward the person you no longer see for periods of time, and make you sure you focus on improving your life. The best way for me is to set goals for when I will see the person, show the progress made while apart, yet how much you missed them.