Nobody is contacted. Nothing is sent.

First, the obvious thing

This app does not message anyone. It has no access to your contacts, it cannot send anything, and nothing you write here reaches the person it is about. Whatever you say, they will not know you said it.

That is worth getting out of the way, because it is the first thing people want to know and the reason most of them will not try it otherwise.

There was no fight

That is what makes it awkward. If there had been a fight there would be a thing to apologise for and a moment to do it in. Instead you left a message for a few days, then a few weeks, and the longer it sat the more a normal reply would have had to explain itself.

Now any message you send has to carry four months of not sending one. So you do not send it, and the gap gets a little wider, and that is the whole mechanism.

What you are actually stuck on

Usually not the friendship. Usually the first sentence.

You do not know whether to be light about it, or to acknowledge the gap, or to pretend there is no gap. Each version implies something different about what happened, and you cannot test any of them, because the test is the thing itself.

So the sentence stays unwritten and the friendship stays in the state it is in — which is not ended, exactly, just parked.

Saying it where it costs nothing

Here you write them: how they joke, how they take things, how they would react to being contacted after this long. Then you open with one of the versions and see what it feels like to have said it.

It is not them. It cannot tell you how they will actually respond, and if you go in wanting that reassurance you will not get it honestly. What it gives you is the experience of having started, once, without the cost of starting.

A fair number of people find the sentence here and then send the real one. That is a good outcome and the app is glad to lose the conversation.