Tenants broke up and one wants off the lease. Forms? (MA)

[Kelsey G.]

My tenants have broken up and both agreed the boyfriend will move out. No domestic disputes or anything and should be clean and easy. I am completely fine with it - she lived there alone before and always paid on time, great tenant. How should I proceed with changing the lease? I read that someone would just have her sign a new lease, but I was hoping there was a form I can give them both to sign acknowledging his departure and therefore removing him from responsibilities. Can you please let me know what you think the best course of action would be?