Anti Social

I got to admit i'm having the 'anti-social mind' after my internship. It's weird though, i used to be so (too/over) friendly last time. And now, sometimes i just lazy to talk to some people. Fortunately, i am still as usual to those old buddies. But to those stranger-friends, i really tired of 'entertaining' them. Sometimes, when I saw them ahead, i would pretend i didnt see them by looking elsewhere or pretend thinking something. Of course, it's unavoidable to greet them by waving my hand slightly or a smile when we have a direct confrontation. It would be a bit rude to ignore people when they know you saw them.

Sometimes, when people invite me for some gathering or events, i would always reject the invitation. Unless it's a bunch of close friends (which rarely the case), i will not attend. Usually it's more to a situation in which a few close friends together with a few stranger-friends. And those stranger-friends are the reasons that i declined the invitation.

Hard to deny, some friends are getting more distant. They are degrading from Friends level to Stranger-friends. How could one keep the friendship working without interacting with each other?

The greatest problem of all, is i dun even try to change this anti social mind. Though i do feel quite lonely often, i do not intend to change the way it is. And i'm totally okay with the current situation.

Anyway, after my short analysis, i figure the reason of being antisocial could be one or combination of those:
1. After internship, things become dull and less interesting, thus losing the socializing spirit.
2. My batchmates are having their internship now, which makes me pretty lonely in uni. The ratio of close friends to stranger-friends is imbalance.
3. My seniors had graduated while there are many other young and super young juniors around. It makes the ratio of people-i-know to people-i-dunno imbalance.
4. I simply getting older, and not as enthusiastic as before.

Should I change?