In this AU before GF dated BF and Pico, she was in an abusive relationship with Cassandra, her toxic ex-girlfriend.

She put up with this abuse for several months, until she finally had the courage and the strength to say, "I've had enough and I deserve better."

The way she broke up with Cass is the same way Marceline broke up with PB in the song 'Woke Up' in their past.

After the song finished, Cass didn't say a word and got the message but in a bad way, and just left.

And after so, GF is living her single life and finally becoming her own person again.