Once or twice a week I have my boyfriend spend the night.Can my landlord dictate who I have in the apartment?

Do you have a lease? What does it say?

If you do not have a lease and the landlord has said you cannot have overnight company he/she can evict you with property notice - I know it isn't fair, but you live in your apartment at the whim of the landlord.

Many leases say something to the effect that everyone staying there must be on the lease. This can get into a legal quagmire, but landlords can make it tough for you in all sorts of ways - jacking your rent way up next time, limiting parking, not renewing your lease. It's never good to have an adversarial relationship with one.