Trouble Getting a Mortgage

[Moira Mosley-Duffy]

I have been declined for a mortgage because I don't pay rent. My boyfriend pays our rent (which is high) and my lending bank has told me that they have to consider that I would be paying all of the rent someday, which precludes me from any large loans. I asked if it would be possible to calculate using the average bay area rent of a single person, or even half of our current rent, but they told me that they need to assume I would be paying the total rent. 

Does this seem right/normal? I am wondering if I should just go to another bank and try again or if we should just apply for a joint mortgage. He's not interested in investing in real estate so I'm not super keen on having his name on a mortgage for a building that I have paid the full down payment on and am managing--but, I trust him so maybe it wouldn't be so bad?

Details:

current rent in bay area is $3,000

my salary is around $60,000

have saved $35,000+ for down payment

looking at duplexes and triplexes around ~$150,000-170,000