"We need to talk" means the sender has already been thinking about something for a while and has decided it cannot stay unsaid. It is not automatically a breakup — but it does mean the topic is significant enough that they did not want to raise it in passing.
The dynamic underneath: The phrase creates an information gap, and anxious minds fill gaps with worst-case stories. The sender is usually managing their own discomfort by scheduling the conversation rather than starting it. Asking for the topic — not the verdict — shrinks the gap without forcing the whole discussion over text.
Replies you can send: Ask for the topic — "Of course. Can you tell me roughly what it is about so I am not guessing until then?" | Set a time — "Yes, let us do it properly. Tonight after 8, or tomorrow morning?" | Name the spiral — "Happy to talk. Open messages like that send my head spinning, so even one line about the subject would help."
Does "we need to talk" mean a breakup? Not usually. It most often precedes a boundary, a complaint or a decision. Breakups are one possibility among several, not the default meaning.
Should I push for the conversation over text? Ask for the subject, not the full conversation. Difficult topics handled over text tend to escalate because tone is invisible.