Tenants want to break lease

[John Pelaez]

I have a duplex (side by side). Side A signed a lease for 1 yr that starts Sep 1. They are inherited tenants. They are a couple, that's dating. The guy notifies me that he doesn't like her anymore and is wanting to move because he cant stand her. He tells me that its ok for him to move as long as she pays the rent. I tell him that both of you are responsible for the rent since you both signed the lease. Rent has been paid on time as well as deposit. Is there anymore I should be concerned about? What are my steps if he bails and leaves her? Together they are able to pay rent, but separately, I doubt she would be able to. If I end up having to evict her for non-payment, how do I go after him?