I own a single family with four girls renting it out. They all signed one single lease but split the rent evenly amongst them. I had a call from one of the tenants yesterday explaining that she wants to move out of the house and in with her boyfriend, asking if she can break the lease. 

What is a good option here? I could tell her she can't break the lease, but I think providing a real solution may be a better and more frictionless option. My thought is to give her 60 days to find a new tenant to take over her lease, and I'd obviously look in that time as well. 

Thoughts? 

Ask the other 3 if this is okay with them. If it is let the one go and look for another.

Is this student housing ?

@Rich Rodman  Allowing her to sublet is generous enough. You don't need to give her a time frame. She's an adult who signed a contract and, presumably, knows how to use the internet. You don't need to assist her. You do need to screen anyone she finds and have both her and the new tenant sign documents. She can move out whenever she finds a suitable replacement whether that be tomorrow or 6 months from now. If she wants her deposit back, the new tenant needs to pay a deposit. 

Do all 4 pay you separately? I would just do a contract amendment to remove her as long as the other roommates agree and require one payment be made for rent. That way they have to figure it out among themselves. I have a lease break fee written into my leases as well. If the other tenants can't afford the house without the 4th roommate then she is out of luck. If they agree to let her leave and get a new girl, I would make them sign a new lease with those changes in it to deter this from happening again. 

If you have one single lease then they should all, individually be fully responsible for the entire lease. If one tenant wants to move out, the other 3 will have to step up their split until a 4th is found or the one leaving can be held accountable by the other 3 until you find a 4th. 

This problem is between the 4 girls not you. Your only real solution is to help them find a new roommate but they are still responsible for the full rent.

Not your problem.  Don’t get involved.  Hopefully you made the contract joint and several. If the other 3 girls allow the 4th girl to leave, the remaining girls still owe full amount. If they want to bring in a new 4th, screen as you normally would.

Its up to the other women 

But they all remain liable

I would not allow a sublease