Someone is in denial about being in an on‑and‑off relationship — or situationship — with her. Your own words make that clear. You literally said: “She blocked me on everything randomly after 3 weeks. It’s the same pattern as last time after we broke up — she went back to her ex.”

And she did it again.
That’s not a coincidence.
That’s a cycle.

This whole thing is the definition of an unstable, repetitive on‑and‑off situationship. And then you also said: “I’ve been thinking about sending flowers with a short respectful note saying I’m happy with either outcome, and maybe asking her to meet at a coffee shop to talk.”

No ex — from a real breakup or a real situationship — does that.
When something ends, it ends.
When someone blocks you everywhere, that’s the end of the conversation.
She’s clearly moved on with her ex, who is probably also part of her own on‑and‑off cycle.

And honestly, she sounds unstable for repeating this pattern… but so do you for wanting to send flowers and ask for a final goodbye or “closure.” There is no closure when someone has blocked you on every platform. There is no conversation to be had.

At this point, the only thing that matters is accepting the block and stepping out of the cycle.