[Landlord-US-CA] Tenant on Tenant domestic Violence

I have been renting to a couple, and their 3 kids. Everything has gone great for the past 3 years. Excellent communication, they take great care of the home and they pay rent on time, never late in 3 years. Recently one tenant informed me she is no longer living in the home do to a domestic violence situation experienced with her fiancé (and father of her children). We live in California where Under California Civil Code 1946.7, a tenant who is the victim of domestic violence has the right to cancel the lease as long as they have met the documentation requirement. I expressed my sympathy, provided resources, asked if she needed assistance obtaining her property and confirmed she would not have any difficulties with me following the law.

My question would be how to handle the lease with the fiancé? My understanding is i could potentially have the legal authority to evict for just cause but i am not required to do so as he would still have the responsibility to continue paying the lease.

They have both paid for July's rent (i understand i would return a prorated portion of her rent upon receiving the documentation), i have attempted to talk to the fiancé by phone, text and email with no response. I do not believe he will be able to pay the rent on his own. My initial thought was to come up with an agreement where he would voluntarily vacate the home and i would return his portion of the security deposit even considering prorating the rent as an incentive to leave quickly.

Any advance would be appreciated, thank you.