Eviction laws and dealing with tenets with guests

[Jason Bigelow]

I live in Michigan and my landlord has just threatened to evict me for having my girlfriend overnight too often. She stays overnight about 10-15 times a month but there is nothing in the lease referring to guests. The lease does mention "Premises shall not be occupied by greater number of persons than the number specified in the rental application without the written permission of the landlord." She has her own apartment that she lives in and I stay there occasionally as well. She is not here while I am not here. He said that I can pay an extra $30 a month if I wanted her to visit that often but I don't feel like it is right for him to charge me extra. Are there rules about how many nights a guest can stay in a month? Am I in the wrong here? If I am evicted, am I out my security deposit most likely?