Couple broke up, one left, how to proceed legally

[Harrison Fortier]

I have a couple on a 1 year lease. They are about 1/2 way through. They broke up and one of them moved out and contacted me about getting out of the lease. Let's call her Mary. The other tenant told me they intend to stay and will keep paying the rent. Let's call him Sam. Sam has been covering the rent himself, so I'm not worried about rent not being paid. Sam also would like Mary off the lease. It seems to me that it would be best to write up a new lease with only Sam on it. However my concern is that technically this could be viewed as an eviction of Mary? I was thinking of having Mary write me a letter that says she moved out on xyz date, has abandoned any property left at the leased premises (if any), and wants to break the lease ASAP. I tried googling around to see what the correct legal thing to do in situations like this is, but couldn't find anything. Thoughts?