We were sitting together

Yes, we were sitting together in the same table just now.
3 of us at the same table at FCM cafe.
Same thing happened 1 and a half year ago.
Sitting together but the feel seems to be so much different.
The last time we were sitting together was at the library
Studying together, chat together and joke together
We even went to 1U together, drink and eat together.
But now, seems like everything have changed.
It's so much different than before.
A friendship that changed so much during this year.
Even now we got a chance to meet up in campus,
it's just. "HI and BYE"
No more conversations, no more jokes.
I was expecting for some conversation with you over there
At first when JC wanted me to sit down and joined you guys for normal chatting
I couldn't make a decision. What came into my mind was to find an excuse for leaving there. It's because i feel sad for seeing you sitting opposite me but we got nothing to talk about.
But eventually I think I should try, at least give a chance for our friendship
But till the end, I couldn't find any topic to start the conversation with you.
Sitting alone looking at you chatting with her.
A friend of mine, has gone to be a stranger now.
It's kinda hurt to feel this.
A person that I can talk to heart by heart
Has now changed to be so weird when meeting each other.
What have I done wrongly that made the situation to be like this?
I really don't know what's the problem.
I want our friendship back!!
What can I do?
Please...