Originally Posted by STT Resident
That's incorrect. All parties who sign a contractual agreement are responsible for the fulfillment of its terms and conditions and can only be released by the agreement of the other parties and, in the case of a rental, the landlord.
But in this case, the terms have already been fulfilled. The lease is up. If the landlord and remaining tenant decide to resign a new lease, that is between them.
In my book, once a lease is month to month, any individual party can give notice and move out. The remaining tenants should make sure to collect from the person leaving for any damage done by them during their time there, or refund them their share of deposit if applicable, because the last person there is usually going to be the one held responsible for any damage, regardless of who caused it.
Whether or not the LL will agree to continue renting to the other party on their own is another matter. We've had that happen on multiple occasions. We signed a lease with persons A & B based on person B's credit and employment. Once the lease is up, person B wants to move out, but person A wants to stay but doesn't meet our requirements. So when person B gives notice to us, we give notice to person A.