No.
Huntress is the forest wizard that ends up being Finns final and off/on long-term life partner.
The second season of Fionna and Cake is all about her and Finn. This is from that. (The first season is all about Simon and Betty.)
Fionna and Cake is art. If you dismissed it like I did thinking it was "just" a spin off, watch it. It takes the world and themes of AT and combines them with genuine heartfelt writing aimed at the fans who have become adults.