Buffy doesn't remember she's the slayer, gets tattoos and peircings, Spike travels with her

In a post apocolypse world Buffy and Spike travel together. She doesn't remember anything of her previous life. Spike knows but doesn't tell her. Eventually she goes back to Sunnydale and finds Willow and remembers everything. Then she has Willow do a forgetting spell again and the whole cycle starts over again. In the end, you learn that this same cycle has already happened a few times. Sometimes Spike thinks of committing suicide.

That's The Ballad of Randy and Joan by Annie Sewell-Jennings. Such a great story!

That Sound like The Ballad of Randy and Joan By Annie Sewell-Jennings

Yes!!! Thank you both very much. I was looking through herself's stories because I knew it was poignant and angsty. I probably never would have found it.