Why doesn't he reply sometimes?

Anonymous
I find this so odd. I know not everyone is a "texter," and so perhaps this may immediately not be understood... Personally, I do prefer the phone if in person isn't possible.

He and I only text. We haven't video chatted in months.

We have entire conversations in text.
This was his thing that he brought to the table.

It really is odd to me how he selectively doesn't respond.

I could NEVER not respond to a photo, or to him telling me something.

I am absolutely not overbearing or anything. I'm very easy to give space.

I reached out to him earlier and it was the only text between us today. It was a 2 line text about work stress.

And after I was his pocket therapist all day the previous day about his own work woes, he ignored me...

He's not busy. He's done this before, like if I send him a pic or share info with him. Ignored.

I just want to know why. Is it a test? Is it to make me upset? Is it to make me scramble to find a way to get him to respond? (I wouldn't dare).
Updates
+1 y
Also, he blows up my phone, flirts, sends me pics of him all the time. We live in different states but have been friends a while. At first glance it may seem he's not "interested," but I don't see this as having anything to do with that.
Updates
+1 y
Next day, still haven't heard.
Why doesn't he reply sometimes?
4 Opinion