See, if I'm the last one who has sent a message to other people, and they never reply, I start to wonder whether or not I've managed to:
a) made a fool of myself
b) sent something rude or inappropriate
c) sent what's known as the "irrelevant and unnecessary" text
Which has ultimately caused the person who I was texting to stop replying.
On the other hand, there are just some cases during these kinds of conversations where you'll end up being in a position where you have nothing else to say. Though to be fair, I think that instead of using the excuse of "have nothing else to say", it's probably more like this: