How long can my boyfriend stay over before it violates my lease?

[Kendall Donnelly]

How long can my boyfriend stay over before it violates my lease? I'm 35 weeks pregnant with our child. He lives and pays rent an hour away from me. 
We have no plans to live together. 
I just moved into my new apartment a month ago. He's here maybe 3-4 consecutive days every other week for our prenatal appointments and to spend some time together. 
The other day, manager let me know that he can't live here, it violates the lease, but offered to let me add him.
I just assured her that he's not living with me. But the way she was talking to me, has me concerned.

The lease doesn't say anything about guests. But the house rules say no more than 14 days a year. 

I was told that house rules that modify the lease are not enforceable.

"Since your lease does not address it, your b/f can stay as often as he pleases. House rules cannot substantially modify the terms of a lease and imposing guest stay limits would be a substantial modification of the terms of the lease"

[Jean Bolger]

Your landlord probably has that guest clause in the lease to avoid tenants bringing in unqualified room mates that would not have passed the tenant screening process. Here's an example: Single person passes background and credit check and moves in. A few weeks later there is a "guest" staying there, who just happens to be the tenant's boyfriend, who just happens to have a criminal record and would not pass the screening...

Now, I'm NOT at all saying or implying that this has any similarity to your situation. I'm just trying to show why your landlord might have such a rule in place, and why adding your boyfriend to the lease might be a more acceptable way of dealing with the situation from the landlord's perspective. Hope this helps, and good luck!