Lease Cancellation Question from Landlord

[Chris Svendsen]

I have a single family home used as a student rental.  I have a tenant who signed a two year lease but wants out after the first year.  I had something pop up in my brain after talking to her as to whether I could actually let her out of the lease legally.  What I mean is that the lease is for two years.  If i let her out after first year is that setting me up to where if I do not let someone else out of lease I am breaking some fair housing law?  Reason I ask is I had another tenant before who wanted to get out of lease and told her no.  Now, I am possibly going to let this tenant out of lease with agreement that security deposit will be lost and she is responsible to assist in finding a replacement, however would not be responsible for any remaining rent due after the first years payments.  

If I allow her out of lease a year early do I now have to let anyone out of lease if they ask?  If so, while lease states tenant is responsible for remainder of lease if break would I be okay to have a lease breaking fee?  Maybe a quarter of the remaining lease amount due?  This is for a building in central Pennsylvania.  Any input you have be welcomed.  I don't want to let one tenant out then have another say they want out and run into legal issues when I tell them sorry but no.  Thank you.