What is observable?
Write down the facts without a motive attached: “I sent a message yesterday; I have not received a reply.” You may not know whether they are busy, upset, unwell or simply offline.
A quiet phone can leave a lot of room for imagination. Start with what happened, then ask for the agreement you actually need.

You sent a message yesterday. They have not answered. You notice yourself checking the phone, rereading an earlier conversation, and wondering whether their feelings changed.
Use this as a way to organize your own observations and requests. It cannot tell you what another person thinks or decide what a relationship means.
Write down the facts without a motive attached: “I sent a message yesterday; I have not received a reply.” You may not know whether they are busy, upset, unwell or simply offline.
Name the interpretation as a possibility: “I am telling myself this means I do not matter.” Naming it helps you treat the feeling seriously without treating the story as proof.
Choose a request that another person can understand and answer. For example: “When plans change, could you send a short update when you have time? I find the uncertainty hard.”
“I noticed I feel unsettled when plans change and I do not hear from you. Could we agree on a quick update when that happens?”
You can change the words, timing and request to fit your circumstances. A respectful request still leaves the other person free to answer.
A communication agreement is useful only when both people can choose it. Repeated silence may also be information about what this relationship can offer; a questionnaire cannot decide that for you.