Do you have problems with finding new friends? You are not extrovert, not popular or simply your standards are high? Maybe you are bohemian and simply, you don't need many friends. Or, you will not enter in other's asses, just for the sake of friendship. Now we come to the next category, do you have problems with keeping friends? How many of your friendships broke with years, and do you still remember old friends with tears in your eyes?
When Hemingway said that "man is not an island" he did not count on new technology, as computers, cell phones, i-phones and similar modern toys. Nowadays any person might gather many virtual friends, with the ability to delete and block anyone who cross limits of good taste. So, we could be lonely islands, but with electronic updates.
If you are one of those people who ask "what is wrong with me?" when friends leave you, don't be desperate. Friends are as flowers, some are just for one season. You will smash your head with questions why dear people left you and forgot that for one dance takes two.
When a friend says "goodbye", this is also breakup, as in love relation. The difference is, you will not miss physical touch and kisses, but you will miss daily coffee, bowling, shopping, gossiping or all other nice things you were doing together.
There is no universal recipe how to keep a friend. Some people will sacrifice own priorities just to gather many friends, but in their background are many compromises. Do you think that your x friend is so happy because he has so many friends? See how much obligations he must do toward them. Call me weird, but when I come at home from my work, I like to rest on my bed without the phone ringing, and even more, everyone who rings on my door is not welcome, unless is someone I dealt a few days before.
Don't mix word antisocial with word selective. You are not obligated to smile with everyone, to explain why you bring some life decisions or to brag about your privacy.
I was thinking a long time why some of my friendships failed. I was too selfish? I was too busy? As time flow, I realize that it became less important. When new people fill space in your life, you will not remember previous ones.
If you lost a friend, maybe something of this happened:
You had no time for a friend, because you moved to another city, found a new job or got married.
You found out that your friend is not so trustful as you thought. You shared secret and someone else knows it too.
Your friend did not respect your husband, wife, parents, children. All this happens when people forget that friends come in a package with their families, other friends, partners. When you discriminate someone's wife or husband, how such friend can like you?
You did progress in career. You found your soulmate. Your friend is still searching, but your happiness is spit in his face. He sees you a treat.
You were inseparable as teenagers, but now your interests are different. So you don't play football in the local club anymore, you don't drink beer with the local gang or ride the bike in free time. Now you are a member of the golf club or literary section.
You don't have to make conflict to lose friends. Sometimes, life circumstances will show you that you grow up before your friend did. Sometimes, end of the friendship is ugly as the breakup. Mutual judgments, skeletons from the closet, bragging about dirty laundry. Once upon a long time ago, you were happy buddies. Today, he is the only shadow from your past and you don't want to remember him.