Breaching the contract of a lease

[Sam S.]

We had 3 students signing a single lease together for my rental property. The lease was clearly written with a clause for "12 months" term. Without any notice, One of the tenants left the country before the lease was over and wrote to me that she wanted to sublet her room to a friend. when I explained that the lease doesn't allow her to sublet, she emailed me back that she wants to terminate her lease.

Doesn't that put all the tenants at a breach with the lease since they signed a single lease together?

These tenants did a lot of damages to my apartment also.