@GC: It could be insanity, aye ._. But that's one way of seeing it.
Consider that he may also have problems himself in that regard (as in...basically anyone who does care, would open contact--in a general case). This doesn't mean that he doesn't really super not care...per se, but just send him a PM (or ask someone to send him a PM in case you were put on an ignore list? Unsure how that thing works).
Then we stop torturing ourselves about thinking why there's no response :/
Because there's the time wherein thought enters. He may need time to think about this too [and many other notes on how interaction occurs]. Leave the note that you're open to communication if or if not he wants, as in leave yourself open to them if the situation doesn't seem like you advancing towards them = the better thing.
In the meantime, busy yourself with people around you who do care :O There's a time for him to respond--and intervening assumptions aside, just leave the door open, with a welcome sign (in analogy) and he will enter when he wants.
Poking generally anyway.
There could be the note of anxiety or the fear of [bad things] in the way. Or on how one judges the other. There are many ways to consider this...rather than the binary 'Do you care? :/'
Like how -long- it took me to open up to people -who pretty much obviously care-, but didn't, because of one single thing that they said, that I already saw that could be easily misinterpreted as something bad.
Or on another occasion, when me and my nephew fought and we got all :I with silence for months...despite me wanting to talk to him and all. When we met up and made up, we looked over and discussed what just happened and there were apparently a ton of assumptions in between that causes...an aversion to communication. It's like a cause-effect thing.
But that's a general note for me anyway
who would like to help ._.
But rather than giving apathy back to him (it doesn't...like, help a lot. Sure, it may disassociate your 'care' to him but...that doesn't help in general, from much personal experience), just leave an open note for him is all I'm saying, and then continue on like that.
...That's actually like being apathetic without being literally apathetic. I think. Like, you know you're open to conversation--so instead of advancing on them (who may be reluctant), you leave them a note like "I'm sorry for the things that got in the way--so let's begin anew; whenever you wish to speak to me again, I'm open" and then the choice is now theirs while in the meantime, you busy yourself with people who presently are with you who do care.
But that's just me anyway. I do hope this clears up though.
Edit: SalmonGod has a point ._. Existentialism is a nice thing, and no matter who we are, we all have control over our lives in full.