Hello,
My boyfriend moved into my apartment, the lease is in my name. My landlord knows about this, but now he wants my boyfriend to be added to the lease. Legally can he do that, what if I want the lease to be in my name only. Can he force me to add him?

Check your lease. If the boyfriend isn't on it, he's a guest, and many leases will limit how long guests can stay. So if you don't add him, be prepared for the landlord to invoke that clause and whatever penalties or actions apply.