Can't be Facebook friends with exes

Every once in a while, I log onto Facebook to check up on what's going on with who I know.  One person I haven't seen much activity from is an ex of mine.  I don't have any exes as Facebook friends (interpret that as you wish) except for this one who I got along with after we broke up.

Thinking about sending him a note, I type in his name in the search box and see he unfriended me.  Odd.  Not too long ago, he posted on my wall, wanting to start a conversation (which I don't like; send me a private message instead if you want to talk).

Wanting to get to the bottom of things, I write a private message, saying I was going to send him a note but saw we were no longer Facebook friends.

His tone was rather brusque and to the point.

"We haven't spoken in a while."

I say I haven't spoken to a lot of people since all of my friends are busy (i.e. work, families, etc.) and asked if he wanted to grab a coffee and catch up.

"There's nothing more to say."

Ouch.

There's a line about exes:  the one thing they all have in common is you.

He was the last bastion of proof that exes could be friendly with one another.  As it turns out, I guess I can't be with any of mine.  It isn't through lack of trying.  There's nothing wrong with being civil, right?  Maybe we're not meant to be in each others' lives.