It was going well. You were both answering quickly, and then one message didn't get a reply. Two days later it still hasn't. Nothing went wrong that you can point to, which is the part that makes it hard — there is nothing to apologise for and nothing to fix.
Send this
Court has reconvened. You're late to your charm defense hearing. Jury's unimpressed. Opening statements?
The thing to give up on is finding out why. Whatever the reason was, she is not going to type it, and asking turns a quiet thread into a conversation about the thread. What is left is the only part you control: what the next message is like to receive. A conversation that died of nothing can be restarted by anything, as long as the anything does not mention the dying.
You are naming the silence, lightly. Someone who was enjoying the conversation will play along; someone who had already moved on will not answer, and that is the same answer you were already holding. What it does not do is show her you were counting the days.
- Don't send
Hey, just making sure you got my last message?
It pretends to be about the technology and is not. She got it. What it actually reports is that the silence has been on your mind long enough to write about.
- Don't send
Too busy for me, huh?
The resentment comes through the joke, and it asks her to feel bad enough to reply. A reply produced that way is worth less than the silence was.
