Leaving them on read doesn’t end the problem. It just gives it more time to grow.

Silence feels like an ending and functions as a pause. The problem stays exactly where it was, and the other person fills the gap with a story that is almost always worse than the truth, because uncertainty reaches for the unkindest explanation available. Meanwhile the reply gets harder to write every day you leave it.

Send something short today, even if it is not the full answer. I saw this and I have been avoiding it, give me until tomorrow. That sentence costs nothing and stops the growth immediately, which is most of what needed doing.