Name the specific thing, take your part without conditions, leave your grievance out of it — then send it once and let them decide. Including an honest answer on whether you should be reaching out at all.
It cancels itself in the same sentence, and the other person hears only the second half. Your complaint is real — it's just a different conversation, and bundling them means neither gets heard.
A vague apology reads as wanting the discomfort to stop rather than as understanding what happened. Naming the specific thing is what makes it land, and it's the part people avoid.
And that converts an apology into pressure. One message and then silence on your side is what leaves them free to answer — chasing takes that away and reliably makes things worse.
Sometimes the answer is no, or not yet. If the other person treated you badly, or this is one instance of a pattern, a well-written apology just invites more of the same.