You are very likely a tenant and your eviction would be subject to the normal legal process in CA.
That being said, your agreement to leave when she asks assuming the BF-GF relationship has ended, would make things much easier for you and would reduce the chances that subsequent issues might flare up that would lead to unnecessary trouble downstream.
I assume that you are no longer boyfriend, girlfriend, so you now are a tenant, except there may be a problem if you are the only other person living there.
She might use the lodger rule to ask you to leave in the same period as you pay rent. If you pay her every 30 days, she can ask you to leave after 30 days and she might not have to evict you. She could then call the police and have them remove you.
But you didn't go in as a lodger, so I believe you are protected as a tenant. I have never had this come up yet in my practice, and the lodger rules are not that old, but it is something to think about. I hope she doesn't know about this law.
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