What I Loved
First, overall, it's a good script. For the most part, your descriptions are clear, themes are strong, and there's some good dialogue.
I really like the dialogue between Lottie and Kaya. At first it seemed too abrupt, the transition from their quirky, romantic beginning into the abusive scenes -- but on reflection, I thought about how quickly that can happen. There's the old cliche about lesbians bringing a U-Haul to the second date and wanting to be immediately domestic. And for some people, domesticity means a pattern of abuse because it's the only way they know.
Kaya's description of her life engenders real sympathy, which makes it seem more of a betrayal when she shows her abusive side. This also fits real life; many abusers really do have their own sad stories, but then take advantage of the sympathy they earn, because they're manipulative.
When Lottie's walking with her Gal Pal, their dialogue is notably more pedestrian than Lottie's dialogue with Kaya. Is this deliberate? If so, it works. Sometimes in a codependent abusive relationship, the abused party finds that relationship more intense and interesting (for a while, anyway) than relationships with "nice" people.
What I'd Love To See
It's a very simple narrative, rotated laterally a bit by the combination of narration and flashback. I'd try and go a little lighter on the narration. It's clear and efficient, but has the inherent problem of distancing the viewer from the story. Being told something is never as powerful as being shown it, so I'd try to bring out more in dialogue (in flashback scenes), less in narration.
Speaking personally, I may have absorbed as many scripts about women being fucked over as I can take. That's not a flaw of your script, just my personal experience.